Design of an implant for cartilage repair

ABSTRACT

Embodiments of the present disclosure relate to design methods for designing a mandrel for hammering, pressing and/or pushing an implant into position in a recess made in a joint and firmly attach the implant to the bone of a patient, the mandrel comprising a contacting surface adapted to be in contact with an articulate surface of the implant to be inserted, the method comprising designing the contacting surface of the mandrel to fit the articulate surface of the implant in that the contacting surface of the mandrel has a cross-sectional profile corresponding to the cross-sectional profile of the implant.

CROSS-REFERENCE TO PRIOR APPLICATIONS

This application is a continuation-in-part application of U.S. patentapplication Ser. No. 15/388,920, filed on Dec. 22, 2016, which is acontinuation-in-part application of U.S. patent application Ser. No.15/018,812, filed on Feb. 8, 2016, which is a continuation-in-partapplication of U.S. patent application Ser. No. 14/342,302, filed Apr.11, 2014, now U.S. Pat. No. 9,254,196, issued Feb. 9, 2016, which is a §371 National Stage Application of PCT International Application No.PCT/EP2012/067024 filed Aug. 31, 2012, which claims priority to EuropeanPatent Application No. 11179923.5 filed Sep. 2, 2011 and U.S.Provisional No. 61/530,497 filed Sep. 2, 2011, each of which is hereinincorporated by reference in its entirety.

FIELD OF THE DISCLOSURE

This disclosure relates in general to the field of orthopedic surgeryand to surgery kits, kits of tools and medical implants. Moreparticularly embodiments of the present disclosure relate to designmethods for designing the contacting surface of a mandrel to fit thearticulate surface of an individually customized implant to be used forreplacement or repair of damaged cartilage at an articular surface in ajoint such as a knee, hip, toe and shoulder.

BACKGROUND General Background

Pain and overuse disorders of the joints of the body is a commonproblem. For instance, one of the most important joints which are liableto wearing and disease is the knee. The knee provides support andmobility and is the largest and strongest joint in the body. Pain in theknee can be caused by for example injury, arthritis or infection. Theweight-bearing and articulating surfaces of the knees, and of otherjoints, are covered with a layer of soft tissue that typically comprisesa significant amount of hyaline cartilage. The friction between thecartilage and the surrounding parts of the joint is very low, whichfacilitates movement of the joints under high pressure. The cartilage ishowever prone to damage due to disease, injury or chronic wear. Moreoverit does not readily heal after damages, as opposed to other connectivetissue, and if healed the durable hyaline cartilage is often replaced byless durable fibrocartilage. This means that damages of the cartilagegradually become worse. Along with injury/disease comes a problem withpain which results in handicap and loss of function. It is thereforeimportant to have efficient means and methods for repairing damagedcartilage in knee joints.

Today's knee prostheses are successful in relieving pain but there is alimit in the lifetime of the prostheses of 10-20 years. The surgicaloperation is demanding and the convalescence time is often around 6-12months. In many cases today, surgery is avoided if training andpainkillers can reduce the pain. Prostheses are therefore foremost forelderly patients in great pain, at the end of the disease process; atotally destroyed joint. There are different kinds of prostheses, suchas half prosthesis, total prosthesis and revision knee, the latter usedafter a prosthesis failure. The materials used in today's kneeprostheses are often a combination of a metal and a polymeric material,but other materials such as ceramics have also been used. The size ofknee prostheses makes it necessary to insert them through open surgery.

Other attempts practiced at various clinics around the world with themain objective to repair or rebuild cartilage include biologicalapproaches such as micro fractures, cartilage cell techniques (e.g.autologous chondrocyte implantation, ACI), periost flap, and autografttransplantation (e.g. mosaicplasty surgery). In mosaicplasty grafts, inthe form of plugs or dowels of healthy cartilage and underlying bone areharvested from non weight-bearing parts of the joint, i.e areas of lowstress in the joint. Such plugs may be denoted osteochondral plugs. Inrelated surgical techniques similarly shaped plugs as those ofmosaicplasty, but made of artificial material, may be used. The plugs ordowels are inserted into drill holes made at the diseased or damagedsite, such that they form a mosaic pattern of healthy cartilage at thesurface of the joint. Osteochondral autograft transfer (OATS) is atechnique similar to mosaicplasty but during the OATS procedure theplugs are usually larger, and therefore only one or two plugs are neededto fill the area of cartilage damage. A difficulty with bothmosaicplasty and OATS is to make sure that the plugs are inserted suchthat they form an even surface. If the plugs are offset from theirintended position, e.g. such that they are tilted or project over thesurrounding cartilage tissue, they may cause increased wear and load onthe joint, resulting in more pain for the patient. The biologicaltreatments have shown only limited results this far, with implicationssuch as high cost, complicated surgery, risk of infection, risk ofloosening, long rehabilitation time, limited suitability for patients ofdifferent ages and the extent and location of damage. They do howeverhave many advantages, especially for young patients who still aregrowing and who have better abilities for self-repair, if thesedifficulties can be overcome.

The advantages of implants have stimulated a further development ofsmaller implants that can be implanted with less invasive surgery. Inthis development there has also been an effort to achieve small jointimplants, suitable for repair of a small cartilage injury that have aminimal influence on the surrounding parts of the joint. In the currentdevelopment, such small implants are designed with an implant body thatmay be formed as a thin plate with a hard surface for facing thearticulate side of the joint and a bone contacting surface for facingthe bone below the damaged part of the cartilage. The shape and thecurvature of the articulate surface of the implant may be designed to besimilar to the shape and the curvature of the part of the joint wherethe implant is inserted. Such implants are designed as mushrooms with animplant body or head and optionally with a peg or a rod projecting fromthe bone contacting side of the implant body for fastening the implantto the bone.

In the surgical operation of implanting small implants, includinggrafted plugs or artifical plugs, it is critical that the implant ispositioned in a precise manner. If the implant is offset from itsintended position it may cause increased wear or load on the joint. Forexample, if the implant is tilted this may result in an edge thatprojects above the cartilage surface and causes wear on the opposingcartilage in the joint. Another example is when the implant is placed ina position with the surface of the implant projecting above the surfaceof the cartilage causing the joint to articulate in an uneven manner andincreasing the load on an opposing point of the joint. For the patient,also small misplacements or deviations from an ideal position may resultin pain, longer time for convalescence or even a surgical operationbeing done in vain and making it more difficult to repair the damage inthe joint. A large burden is therefore placed on the surgeon not tomisplace or misfit the implant. In order to support the surgeon duringthe implant surgery and to improve the positioning of the implantvarious tools and guides that support the surgical procedure have beendeveloped.

Specific Background

During cartilage repair in a joint, different methods are known todayfor repair of cartilage damages. One example is replacing damagedcartilage and thereby repairing a part, namely the damaged part, of thecartilage in the joint instead of replacing the whole joint. Thismethod, replacing a part of the cartilage in the joint using an implant,requires high precision tools. During such a repair it is important thatthe replacement is well fitted in the joint otherwise the implant willstart to move and the repair in the joint will not last for long. Theinstruments on the market today are not user friendly and require muchskills of the surgeon. Several instruments are needed for forming arecess for an implant and may lead to that there is lack of fit for theimplant due to the several steps needed for making a recess. There is aneed for improved instrumentation during these sorts of cartilagerepairs. Improved instrumentation which is easy to use, and which givesthe same result without dependence on which surgeon who is using them.It is also important that the instruments allow for short implantationprocedures.

Some of the surgical tools developed for implant surgery include guidetools having a channel or similar through which the surgical toolsand/or the implant are guided throughout the surgery. Often these guidetools are rather bulky and placed over the damaged site of the cartilagesuch that it is difficult for the surgeon to see the site ofimplantation during surgery. Also it may be difficult to remove debrisand waste that is generated at the implantation site during surgery. Inorder for the surgeon to be able to inspect the implantation site and/orremove such surgery waste, the guide tool has to be removed from thesurgical site in the joint. There is a need for a surgical kit forreplacement or repair of damaged cartilage, and possibly also underlyingbone, at an articular surface in a joint that guides the surgeon,improves the positioning of the implant or the grated or artificialplugs, and that facilitates inspection of the implantation site andremoval of debris during surgery.

PRIOR ART

Examples of prior art disclosing smaller implants and tools forreplacement of damaged cartilage are shown in:

WO2007/014164 A2 describes a kit comprising a plurality of small jointimplants having different predetermined shapes described as circular,oval, L-shaped and triangular and tools for placing the implants and amethod for placing the implant in a joint, e.g. in the knee or otherjoints where there is a need for repair of a cartilage and/or bonedamage. In this piece of prior art each implant shape has a specificguide tool which corresponds to the shape of the implant.

The cartilage damage is repaired by choosing the most suitable implantfrom the different shapes mentioned above. The corresponding guide toolis selected and is used for faster reaming of the area where the implantis to be placed. A drill is used for drilling a hole to accept the postextending from the bone contacting side of the implant. In the end, theimplant is placed on the area reamed or drilled out for the implant.Although it is the intention that the guide tool shall be used for thepreparation of the placement of the implant it is also said that the useof the guide tool is optional, see passage sections [019, 020].

US20030216669 A1 shows methods and compositions for producing articularrepair material used for repairing an articular surface. The method fordesigning an articular implant comprises; taking an image of the joint,reconstructing dimensions of the diseased cartilage surface tocorrespond to normal cartilage and designing the medical implantaccordingly. This prior art also shows a surgical assistance device orsurgical tool for preparing the joint to receive an implant. Thesurgical tool comprises of one or more surfaces or members that conformto the shape of the articular surfaces of the joint. It can includeapertures, slots and/or holes that can accommodate surgical instrumentssuch as drills and saws. (see claim 18, [0029], [175] FIGS. 13, 15, 16),and thus may also be designed and used to control drill alignment, depthand width, for example when preparing a site to receive an implant[0179]. The tool may be single-use or reusable [181]. These surgicaltools (devices) can also be used to remove an area of diseased cartilageand underlying bone or an area slightly larger than the diseasedcartilage and underlying bone [0182].

EP 1 698 307 A1 discloses an instrument for removing cartilage andintroducing an implantable nonwowen into cartilage. The instrument mayfurther comprise a cartilage puncher having a channel through whichfurther instruments, such as surgical spoons or curettes, can be guidedto the cartilage defect ([0028-0029]).

WO2008098061 A2 also shows examples of small articular surface implantsand tools for placement of the implants. The tools and the implant areused to repair damaged articular cartilage areas.

WO2006091686 A2 shows a small implant for replacing a portion of anarticular surface (see the abstract). The implant is placed using arotating excision tool (see page 8 line 25) and the implant is selectedfrom a set (see page 10 line 22-23).

WO 2009111626 shows implants for altering wear patterns of articularsurfaces of joints (see [00190]) and a device and a method for repair ofarticular surfaces, in for example a knee. The implants and methods mayreplace all or a portion of the articular surface and achieve ananatomic or near anatomic fit with the surrounding structures andtissues, the techniques described herein allow for the customization ofthe implant to suit a particular subject, the implant is a mirror imageof the articular surface, see [0057]-[0058]. The implants are selectedfrom predetermined shaped and their location can be optimized for thepatients wear pattern and the wear patterns are assessed by for exampleMRI [0061]-[0063], [0072]. The tools used for placement of the implantsare selected depending on MRI images but not created depending on theimages [00211].

WO2008101090 A2 shows a method for making a large implant suitable for ajoint. The 3D surface of the joint implant is determined using MRI or CTdepicting the damaged that is to be repaired.

US2006/0198877 A1 shows a medical instrument for autologous chondrocytetransplantation.

WO2009/108591 A1 shows a method and tools for repairing an articularcartilage defect and also an implant.

U.S. Pat. No. 6,306,142B1 shows a system and tools for transplanting abone plug from a donor site to a recipient site.

US 2003/0100947 A1 shows a device for repairing articular cartilagedefects.

EP2389905B1 describes a method for designing a surgical kit comprising adrill bit for drilling. Several instruments are needed for making therecess for an implant comprising an extending post.

SUMMARY

The technology disclosed relates to a design method for designing amandrel for hammering, pressing and/or pushing an implant into positionin a recess made in a joint and firmly attach the implant to the bone ofa patient, the mandrel comprising a contacting surface adapted to be incontact with an articulate surface of the implant to be inserted, themethod comprising designing the contacting surface of the mandrel to fitthe articulate surface of the implant in that the contacting surface ofthe mandrel has a cross-sectional profile corresponding to thecross-sectional profile of the implant.

In embodiments, the design method further comprises designing at least aportion of the mandrel surface to have an inverted surface, oressentially inverted surface, to the curvature of the articulate surfaceof the implant to be inserted.

In embodiments, the design method further comprises designing thecross-sectional profile of the contacting surface of the mandrel to havea tolerance in relation to the cross-sectional profile of the articulatesurface of the implant in order to prevent the mandrel from coming intocontact with the surrounding cartilage during insertion of the implantinto the recess.

In embodiments, the design method further comprises receiving image datarepresenting a three-dimensional image of a joint; identifying cartilagedamage in the image data; determining the position of an implant to beused for cartilage repair; simulating a healthy surface of the area ofdamaged cartilage at the determined implant position; designing thearticulate surface of the implant to match the simulated healthysurface; and determining the mandrel surface to have at least one of acorresponding and an inverted curvature to the curvature of thearticulate surface of the implant.

In embodiments, the design method further comprises determining theposition of at least one element and/or positioning mark of the mandrel;and designing said at least one element and/or positioning mark of themandrel to be adapted for rotational positioning of the mandrel inrelation to the implant.

In embodiments, the design method further comprises designing at leastone element and/or positioning mark of the mandrel to be adapted forrotational positioning the mandrel so that the mandrel surface isdesigned to fit the articulate surface of the implant in that themandrel has a corresponding cross-sectional profile.

In embodiments, the design method further comprises designing at leastone element and/or positioning mark of the mandrel to be adapted forrotational positioning the mandrel so that the mandrel surface fits thearticulate surface of the implant.

In embodiments, the design method further comprises designing at leastone element and/or positioning mark of the mandrel to be adapted forrotational positioning the mandrel in relation to a positioning mark ofthe implant.

In embodiments, the design method further comprises designing at leastone element and/or positioning mark of the mandrel to be adapted forrotational positioning the mandrel in relation to a positioning mark tobe made on the side of the recess where the implant is to be inserted.

In embodiments, the design method further comprises designing at leastone element and/or positioning mark of the mandrel to be pointing in ananatomic dependent direction, said at least one element and/orpositioning mark thereby indicating a correct orientation of the mandrelwhen inserted into the recess where the implant is to be inserted.

In embodiments, the implant is an individually customized implantdesigned with an articulate surface having a shape and curvature whichis simulating a healthy surface at the determined implant position wherethe implant is to be inserted, the design method further comprisingdesigning at least one element and/or positioning mark of the mandrel tobe adapted for rotational positioning the mandrel in relation to atleast one element and/or positioning mark of the implant and apositioning mark to be made on the side of a recess.

In embodiments, the articulate surface of the implant is designed tomatch a healthy surface at the determined implant position and thehealthy surface is simulated based on image data representing athree-dimensional image of a joint and the curvature of the cartilageimmediately surrounding the area of damaged cartilage.

In embodiments, the contacting surface of the mandrel is designed to bea corresponding surface to a healthy surface at a determined implantposition of a joint and the healthy surface is simulated based on imagedata representing a three-dimensional image of the joint and thecurvature of the cartilage immediately surrounding the area of damagedcartilage.

In embodiments, the contacting surface of the mandrel is designed to bean inverted surface to a healthy surface at a determined implantposition of a joint, and the healthy surface is simulated based on imagedata representing a three-dimensional image of the joint and thecurvature of the cartilage immediately surrounding the area of damagedcartilage.

In embodiments, the design method further comprises providing at leastone element and/or a positioning mark on the mandrel such that thepositioning mark is visible for a surgeon and is adapted to be used forindicating a rotational position of the mandrel in relation to theimplant to the surgeon.

In embodiments, the design method further comprises providing at leastone element and/or a positioning mark on the mandrel as a marking, suchas e.g. a dot, or groove in the circumference of the contacting surfaceof the mandrel.

The technology disclosed also relates to a mandrel for hammering,pressing and/or pushing an implant in position and firmly attach animplant to the bone of a patient, said mandrel comprising a contactingsurface that fits the articulate surface of an implant to be insertedusing the mandrel in that the mandrel has a correspondingcross-sectional profile to the articulate surface of the implant.

In embodiments, the contacting surface of the mandrel is an invertedsurface to the curvature of the articulate surface of the implant to beinserted in a joint using the mandrel.

In embodiments, the mandrel further comprises at least one elementand/or positioning mark adapted for rotational positioning of themandrel in relation to at least one of an anatomic dependent direction,at least one element and/or positioning mark on the surface of theimplant, an element and/or a positioning mark of the guide tool, and amark to be made on side of a recess to be made at the determined implantposition.

In embodiments, said at least one element and/or positioning mark forrotational positioning the mandrel includes at least one of aprotrusion, a groove, a notch, a recess, a hole, a marking or shape fitelement adapted for rotational positioning the mandrel.

In embodiments, the mandrel further comprises a grip portion that has asmaller diameter close to the contacting surface than at the middle ofthe grip portion, in order for the point of gravity to lie in the handof the surgeon using the mandrel.

Embodiments of the present disclosure relate to design methods fordesigning the surface of an individually customized implant forcartilage repair, comprising receiving image data representing a threedimensional image of a joint, identifying cartilage damage in the imagedata, determining the position of an implant to be used for cartilagerepair, simulating a healthy surface at the determined implant position,and designing the surface of the implant to match the simulated healthysurface.

In embodiments, the healthy surface is simulated based on the curvatureof the cartilage immediately surrounding the area of damaged cartilage.

In embodiments, the simulation comprises an interpolation, which may bea tangent interpolation.

In embodiments, an implant is designed based on a determined implantposition and the designed surface.

In embodiments, the determining of the position of the implant involvespositioning the implant so that the implant hat (H) will at all pointsbe thick enough to ensure mechanical stability, and preferably alsothick enough to ensure firm anchoring towards cartilage and bone. Inembodiments, the positioning of the implant involves positioning theimplant so that the implant hat (H) at each point of its circumferencepenetrates at least a predetermined minimum depth into the bone. Inembodiments, the positioning of the implant involves tilting the implantaxis (A) so that the maximum penetration depth into the bone along thecircumference of the implant hat (H) is minimized. In embodiments, thepositioning of the implant involves minimizing the total volume of boneand/or cartilage to be removed for implanting the implant. Inembodiments, the positioning of the implant involves minimizing thesurface area of the implant penetration into the bone.

Embodiments of the present disclosure provides a modular surgical kitcomprising a guide base and a guide body for use with a set of tools anda method for replacing a portion, e.g. diseased area and/or areaslightly larger than disease area, of a joint, e.g. cartilage and/orbone, with an implant or with one or more artificial or grafted bone andcartilage plugs, such as those used for mosaicplasty or OATS. Themodular surgical kit may also comprise the set of tools. The modularsurgical kit is arranged to achieve a near anatomic fit of the implantwith the surrounding structures and tissues as well as facilitating tosurgical procedure.

Embodiments of the present disclosure provides a modular surgical kitfor repair of diseased cartilage at an articulating surface of a joint.It is for use with a medical implant, a grafted plug, or an artificialplug that has an implant body with a predetermined cross-sectionalprofile. The modular surgical kit comprises a guide base with apositioning body and a guide hole through the positioning body. Thepositioning body has a cartilage contact surface that is designed to fitthe contour of cartilage or subchondral bone in the joint in apredetermined area surrounding the site of diseased cartilage. The guidehole has a muzzle on the cartilage contact surface at a positioncorresponding to the site of the diseased cartilage.

The modular surgical kit further comprises a guide body with a guidechannel. The guide channel has a cross-sectional profile that isdesigned to correspond to the cross-sectional profile of the implantbody and also has a muzzle.

The guide channel is positioned in relation to the positioning body suchthat its muzzle emanates at a site corresponding to the site ofimplantation into the bone.

In one embodiment of the modular surgical kit the cartilage contactsurface is custom designed to fit the contour of the cartilage orsubchondral bone of a specific patient. In another embodiment thecartilage contact surface is designed to fit the contour of thecartilage or subchondral bone of an average patient.

In one embodiment of the modular surgical kit, for use e.g. inmosaicplasty or OATS surgery, the guide body comprises at least twoguide channels. Each guide channel has a cross-sectional profile that isdesigned to correspond to the respective cross-sectional profile of atleast two implant bodies.

In a further embodiment of the modular surgical kit the guide channel,having a cross-sectional profile that is designed to correspond to thecross-sectional profile of the implant body, is provided by a guideinsert that is designed to fit in the guide body.

In still another embodiment the modular surgical kit further comprises adrill adjustment device that is arranged to enable adjustment of thedrill depth e.g. in certain length intervals.

In one embodiment the positioning body is arranged with at least onebreakage means for enabling easy removal of part of the positioning bodyby tearing, fracturing or similar breakage. Such means may for examplebe provided by grooves, slots or perforations or other weakening of thestructure.

The positioning body may also be arranged with at least one attachmentmeans for enabling easy attachment of adaptors, pins and other devicesused during surgery, e.g. by snap fit. The modular kit may also furthercomprise adaptors that fit the attachment means, for enabling flexibleattachment of pins and other devices.

In one embodiment the modular surgical kit further comprises an inserttool with a cross-sectional profile that is designed to correspond tothe cross-sectional profile of the guide channel, with a toleranceenabling the insert tool to slide within the guide channel.

Such insert tool may be a cartilage cutting tool that has across-sectional profile that is designed to correspond to thecross-sectional profile of the guide channel, with a tolerance enablingthe cartilage cutting tool to slide within the guide channel. Thecartilage cutting tool comprises a cutting blade with sharp cuttingedges that are able to cut the cartilage in a shape that substantiallycorresponds to the cross-section of the implant body.

The insert tool is in another embodiment a drill and bone remover havinga drill and bone remover body with a cross-sectional profile that isdesigned to correspond to the cross-sectional profile of the guidechannel, with a tolerance enabling the drill and bone remover to slidewithin the guide channel. The drill and bone remover may comprise acentral drill, for drilling a bore to receive the extending post of theimplant, and a bone remover, for cutting a recess in the bone to receivethe implant body of the implant.

The insert tool may further be a mandrel having a mandrel surface thatis designed to fit the articulate surface of the implant. The mandrelalso has a cross-sectional profile that is designed to correspond to thecross-sectional profile of the guide channel, with a tolerance enablingthe mandrel to slide within the guide channel.

In one embodiment the surgical kit further comprises an implant dummyhaving an implant element that is designed to match the implant body andhaving a lower surface that is a replica of the bone contact surface ofthe implant, but comprising no extending post. The surgical kit mayfurther comprise a dummy reference that is arranged to fit to, andpossibly releasably attach to, the guide hole of the guide base. It isarranged to receive the implant dummy, by being provided with a channel.

Embodiments provide an implant specific drill bit.

A first aspect provides a design method designing an implant specificdrill bit 202 comprising steps;

-   -   a. determining or selecting a size and shape of an orthopedic        implant 210 comprising a circular shaped implant body 227 and a        centrally placed circular shaped extending post 23    -   protruding from the bone contacting surface 238 in a        longitudinal y-axis 260 direction of the implant 10; and    -   b. selecting design parameters for the implant specific drill        bit 202 by;    -   selecting the width 240 of the broadest part of the bone remover        226 in a side view to correspond to, or to be slightly smaller        than, the diameter 250 of the implant body 227 of the specific        implant 210 that is to be implanted    -   selecting the rotational volume and the length 272 of the        central drill part 222 to correspond to, or to be slightly        smaller than, the diameter 252 of the extending post 223 of the        specific implant 210 that is to be implanted    -   selecting the curvature of the cutting edge 228 that is placed        anywhere peripherally around or surrounding the central drill        part 222 of the implant specific drill bit 202 to correspond to        the curvature of the bone contacting surface 238 of the implant.    -   In one embodiment the a design method according to the present        disclosure for designing the implant specific drill bit        comprises determining the size and shape of said implant so that        it may either be performed by    -   selecting implants from a kit of implants of different        predetermined sizes; or    -   by individually designing the size and shape of an implant

and wherein the size and shape of the selected implant is correspondingin large or partly or substantially to the size and shape of a cartilagedamage in a specific patient.

A design method according to any of the preceding claims wherein saidcutting edge (28) in side view is designed to correspond to the shape ofat least one side of the bone contacting surface (38) in across-sectional view of the specific implant (10); and wherein the bonecontacting surface (38) is substantially flat or a bone contactingsurface (38) which comprises an protruding anchoring ring portion (36).

Further varieties of the design method according to the disclosurecomprising any of the following optional, individual or combinableaspects;

A design method wherein the volume of the part of the designed implantspecific drill bit (2) which corresponds to fit the implant (10) is0.1-5% smaller than the volume of the implant (10) to be implanted,allowing for press fit of the implant (10) placed in the recess made bythe implant specific drill bit (2) according to the disclosure.

A design method wherein the cutting edge comprises at least one flange(220).

A design method wherein the flange has a length (224) of 0.3-3 mmprotruding from the cutting edge (2) and/or a width 0.3-2.0 mm or0.3-2.0 mm corresponding to the length (235) in a cross-sectional viewof the anchoring ring portion (36) of an implant (10).

A design method wherein the angle 328 between the cutting edge (28) andthe longitudinal y-axis (70) of the implant specific drill bit 202 isdesigned to be 90° or less or for example 80° or less or 70° or lessbased on the selected specific implant and its corresponding angle.

A design method wherein the length 272 of the central drill part (22) ofthe implant specific drill bit is designed to be 2-300 mm correspondingto or slightly longer, or 1-5% longer than the length (82) of theextending post (23) of an specific implant (10).

An implant specific drill bit (2) made due to the design method used fordesigning the product for producing bone cavities for receivingorthopedic implants according to the disclosure wherein said drill bit(2) comprises:

-   -   a drill and bone remover body (20) having a proximal end and a        distal end and a longitudinal axis extending between the        proximal end and the distal end; and    -   a bone remover part (26) located in one end of the bone remover        body (20); and    -   a central drill part (22) protruding from said bone remover part        (26)    -   wherein said bone remover part (26) comprises a cutting edge        (28) which is placed peripherally around the central drill part        (22)

An implant specific drill bit (2) wherein the bone remover part (26)comprises a flat surface or a surface which further comprises flanges(220). A kit comprising an implant specific drill bit (2) designedaccording to claims 1-4 and an implant 10, wherein said an implantspecific drill bit (2) is designed to correspond to the size and shapeof said implant (10).

A implant specific drill bit 202 or a drill and bone remover 202according to the disclosure that is used to drill a hole in the bone atthe site of cartilage damage, for fastening of the extending post 223 ofthe implant 210 in the bone tissue, and simultaneously create a recessin the bone tissue at the site where the implant body 227 is to bereceived. The drill and bone remover 202 comprises a drill and boneremover body 20, a central drill 222 and a bone remover 26. The centraldrill 222 extends from the centre of the drill and bone remover body 20,i.e. corresponding to the position of a centrally placed extending post223 on an implant 210 having a circular implant body 27. The diameter ofthe central drill 222 is the same as, or slightly smaller than, thediameter of the extending post 223 of the implant 210 that is to beimplanted. The bone remover 226 has a cutting edge that is placedperipherally around the central drill 22. The diameter of the boneremover 226 is the same as, or slightly smaller than, the diameter ofthe implant body 227 of the implant 210 that is to be implanted, thuscreating a recess that matches the implant body, in which the implantbody can be received. The cutting edge of the bone remover 226 is hardenough for cutting or carving bone. It may be made of materials such asstainless steel.

The drill and bone remover body 220 may be designed to fit the inside ofthe guide channel of the guide body of a guide tool, with a slighttolerance to allow a sliding movement of the drill and bone remover 202in the guide channel. In other words, the cross-sectional profile of thedrill and bone remover body 220 matches the cross-sectional profile ofthe guide channel as well as the of the implant 10. The fit ensures thecorrect, desired placement of the drill and bone remover 202 on thecartilage surface and thus ensures the precise direction and placementof the drill hole for the extending post 23, as well as the recess forthe implant body 27, in the bone.

The drill and bone remover 202 may also be equipped with a depth gauge7. The depth gauge 207 of the drill and bone remover determines thedepth of the created drill hole as well as the recess for the implantbody 27. The depth gauge 207 has a cross-sectional profile that islarger than the cross sectional profile of the guide channel. The depthgauge 207 will, during the surgical procedure, rest against the top ofthe guide body and/or drill adjustment device 16, thus preventing thedrill and bone remover 202 to drill/carve/cut deeper into the bone. Thedistance between the tip of the cutting edge of the cutter and the depthgauge 7, and the relation between that distance and the length of theguide channel, will determine the depth that the is allowed to go intothe cartilage and/or bone. The depth gauge 207 may be arranged such thatthat distance is adjustable. In a more preferred embodiment the distanceis fixed and instead the drill/cut/carve depth is adjusted by adjustingthe length 31 through the drill adjustment device 16.

BRIEF DESCRIPTION OF THE FIGURES

The present disclosure will be further explained below with reference tothe accompanying drawings, in which:

FIG. 1 shows a schematic overview of an exemplifying method used fordesigning a patient specific surgical kit.

FIG. 2 shows a surgical kit according to one embodiment of thedisclosure, exemplified by a surgical kit for a knee, the surgical kitcomprising a guide base, a guide body and a set of tools.

FIGS. 3a-b shows an exemplifying embodiment of an implant.

FIGS. 3c-f show exemplifying cross-sectional profiles of such implant.

FIGS. 4a-b show an exemplifying embodiment of a grafted plug.

FIGS. 4c-f show exemplifying cross-sectional profiles of such graftedplug.

FIGS. 4g-h show such grafted plugs implanted into bone by use ofmosaicplasty surgery.

FIG. 5a-d show exemplifying embodiments of a guide base according to thepresent disclosure, for use in a knee joint (a-b) and in a toe joint(c-d) respectively.

FIG. 6 shows an exemplifying embodiment of a modular surgical kitaccording to the present disclosure, fur use in a knee joint.

FIG. 7 shows an exemplifying embodiment of a modular surgical kitaccording to the present disclosure, fur use in a toe joint.

FIG. 8 shows an exemplifying embodiment of a guide body according to thepresent disclosure, for use in mosaicplasty surgery.

FIG. 9 shows an exemplifying embodiment of a cartilage cutter.

FIG. 10 shows an exemplifying embodiment of a drill and bone remover.

FIG. 11a shows an exemplifying embodiment of a dummy reference.

FIG. 11b and an implant dummy.

FIG. 12 shows an exemplifying embodiment of a mandrel.

FIGS. 13a-l show exemplifying embodiments of the cross-sectionalprofiles of an implant and tools of the modular surgical kit.

FIG. 14a-t show an exemplifying embodiment of a method for implanting acartilage implant using the modular surgical kit of the presentdisclosure.

FIG. 15 schematically illustrates an implant specific drill bitaccording to an exemplified embodiment of the disclosure.

FIG. 16a schematically illustrates an implant specific drill bitaccording to an exemplified embodiment of the disclosure.

FIG. 16b schematically illustrates an implant for implantation accordingto an exemplified embodiment of the disclosure.

FIG. 17 schematically illustrates use of an implant specific drill bitfor creation of a recess in a joint.

FIG. 18a schematically illustrates an implant specific drill bitaccording to an exemplified embodiment of the disclosure.

FIG. 18b schematically illustrates an implant for implantation accordingto an exemplified embodiment of the disclosure.

FIG. 19a schematically illustrates an implant specific drill bitaccording to an exemplified embodiment of the disclosure.

FIG. 19b schematically illustrates an implant for implantation accordingto an exemplified embodiment of the disclosure.

FIG. 20a shows an exemplified embodiment of an implant specific drillbit comprising a cutting edge on only one side of the longitudinaly-axis of the drill bit and having the rotational volume correspondingto the specific implant.

FIG. 20b schematically illustrates an implant for implantation accordingto an exemplified embodiment of the disclosure.

FIG. 20c shows a perspective view of the implant in FIG. 20 b.

FIG. 21 shows an example of a recess in cartilage and bone tissuedrilled with conventional drilling tools having frayed cartilage andmisaligned cartilage and bone tissue recesses.

FIG. 22 shows an example of two adjacent recesses drilled with drilltools of embodiments drill tools presented herein.

FIG. 23 shows an embodiment of a drill tool with sharp cutting edges andshark fin shape forming edges.

FIGS. 24a and 24b show images of an embodiment of a drill tool withsharp cutting edges and shark fin shape forming edges.

FIGS. 25a and 25b illustrate an embodiment of a drill tool and implant,and show the corresponding shapes of the lower part of the drill tooland the bone contacting part of an implant.

FIGS. 26a-d show the design of an implant having a surface whichcorresponds to a three dimensional (3D) image of a simulated healthycartilage surface.

FIGS. 27a-d show the design of an implant with a surface shapecorresponding to two overlapping circles having a surface whichcorresponds to a three dimensional (3D) image of a simulated healthycartilage surface.

FIGS. 28a-b show an implant positioned at different depths and axistilts in a joint.

FIG. 29 shows an example of a surgical kit designed according to one ormore embodiments of the disclosure.

FIGS. 30-32 show different embodiments of a mandrel according to one ormore embodiments of the disclosure.

FIGS. 33a-b show medical implants according to one or more embodimentsof the disclosure.

FIG. 34 shows a guide tool according to one or more embodiments of thedisclosure.

FIG. 35 shows shows a guide tool according to one or more embodiments ofthe disclosure comprising an implant dummy placed inside the guidechannel of the guide tool.

FIG. 36 shows the use of a mandrel for for hammering, pressing and/orpushing an implant into position in a recess made in a joint, accordingto one or more embodiments of the disclosure.

DETAILED DESCRIPTION

Introduction

This disclosure concerns a surgical kit for use in orthopedic surgery. Asurgical kit according to the disclosure comprises a set of tools forthe implantation of an implant, or one or more grafted plugs orartificial plugs that replaces damaged cartilage, and possibly alsodamaged underlying bone, in a joint.

FIG. 2 shows a surgical kit according to one embodiment of the presentdisclosure, for use in repair of damaged cartilage, and possibly alsodamaged underlying bone, in a knee joint. The surgical kit comprisestools that are adapted to an implant and to a joint; a guide base 12with a positioning body 11 and, attached thereto, a guide body 13. Adrill adjustment device 16 fitting to the guide body 13 may also beincluded in the kit. Further the surgical kit may comprise insert tools,for example a cartilage cutting tool 3: a drill 2, in this exemplifyingembodiment equipped also with a bone remover 26, an implant dummy 36, adummy reference 37 and/or a mandrel 35. Optionally, the kit may alsocomprise the implant to be implanted by use of the surgical kit.

The implant and the set of tools according to the disclosure arepreferably individually designed for a person's joint. The implant andthe set of tools are also optionally individually designed for aspecific person's cartilage individual injury.

Exemplifying embodiments of the disclosure are shown herein which areespecially adapted for cartilage replacement at the femur of a kneejoint, at the talus of the ankle joint and at the joint of a toe. Thedisclosure may however, also have other useful applications, such as forcartilage replacement at an articulating surface at any other joint inthe body, e.g. elbow, finger, hip and shoulder.

The Surgical Kit

This disclosure provides a surgical kit where the successful implantinsertion is less depending on the skills of the surgeon compared topreviously known methods and which facilitates inspection of thesurgical procedure as well as removal of wear and debris during thesurgery. This disclosure provides preferably individually designed toolsand implant. Due to the design and the function of both tools andimplant the surgical kit gives improved implantation precision and aprecise desired placement of the implant in the joint every time. Theprecision of the surgery is “built in” into the design of the tools.

The surgical kit of the disclosure leads to shorter learning curves forthe surgeon since the surgical kit facilitates for quick, simple andreproducible surgery.

In one exemplifying embodiment the implant is intended for replacingdamaged cartilage in a knee. The site where the implant is to beimplanted according to the disclosure is an articular cartilage surfaceincluding, for example, the lateral femoral chondral (LFC) surfaces,medial femoral chondral (MFC) surfaces, trochlea surfaces, patellasurfaces, tibia surfaces (e.g. surfaces of the tuberosities of thetibia), and combinations and portions thereof. For example implants maybe placed on any one of these surfaces.

In another exemplifying embodiment the implant is intended for replacingdamaged cartilage in a toe, for example on the cartilage surfacesbetween the metatarsals and the proximal phalanges bones in a toe.

In another exemplifying embodiment the implant is intended for replacingdamaged cartilage in an ankle, for example on the cartilage surfaces ofthe talus bone.

In a further exemplifying embodiment the implant is intended forreplacing damaged cartilage in a shoulder, for example on thearticulation surfaces between the head of the humerus and the lateralscapula (specifically-the glenoid fossa of the scapula).

The implant is inserted through a small open surgery operation using atool kit where the tools in the tool kits are preferably individuallydesigned or tailored/customized for the person who suffers from theinjury. This leads to decreased suffering of the patient and iseconomically favorable since it leads to shorter convalescence time andless time for the patient at the hospital compared to e.g. more invasiveprosthesis surgeries. By using this optionally individually or partiallyindividually designed surgery kit the implant insertion will be optimaland thus the risk of implant misalignment which is one of the problemsassociated with the common methods used today can be minimized.

Using the surgical kit according to the disclosure, small cartilagedamages will require small implants and in this way combined with thedesign of the guide tool, a surgical operation with little tissue damageand a small open surgery, is needed for the person suffering from a kneeinjury. This gives the effect that minimal modifications on theunderlying bone and surrounding tissue are required when preparing forthe implant surgery. If there are damages in the underlying bone, theimplant thickness may however be adjusted to also replace damaged bone.Using implants according to the present disclosure makes it possible torepair cartilage defects at a much earlier stage than is normally done.This early replacement of damaged cartilage may postpone or preventosteoarthritis.

An object of the disclosure is to solve the problem of repairingdamaged, injured or diseased cartilage in knees, toes, ankle, hips,elbows or shoulders by providing an implant that will have betterplacement and thus a seamless placement in the cartilage.

The benefits from the implant according to the disclosure are relieffrom pain and discomfort such as swelling in the joint and also therestoration of a smooth, continuous articulating surface for futuremobility. The implant and the tool kit of the present disclosure alsofacilitates for the return to normal activity with rapid recovery time,possibility to postpone or avoid total knee replacement surgery. A lesstraumatic surgery procedure is used and potentially faster recoveryafter surgery.

Implants

The surgical kit of the present disclosure may be used for implantationof for example small implants and of bone and cartilage plugs, such asosteochondral plugs, or artificial plugs. Examples of implants to beused with the surgical kit of the disclosure will be given below. Thekit may however be used with any implant having an implant body with across-sectional profile that corresponds to the cross-sectional profilethe guide channel of the guide body 13 (see below).

Small Implant

FIGS. 3a-3b shows an embodiment of a medical implant 10 that may be usedwith a surgical kit according to the present disclosure. The implantcomprises an implant body 27 and an extending post 23. The implant body27 has an articulate surface (first surface) 15 configured to face thearticulating part of the joint and a bone contact surface (secondsurface) 21 configured to face bone structure in the joint. An extendingpost 23 extends from the bone contact surface 21. Between the articulatesurface 15 and the bone contact surface 21 there is a cartilagecontacting surface 19.

The implant may be specially designed, depending on the appearance ofthe knee and the shape of the damage and in order to resemble the body'sown parts, having a surface which preferably corresponds to a threedimensional (3D) image of a simulated healthy cartilage surface. Theimplant can thus be tailor-made to fit each patient's damaged part ofthe joint. Alternatively, the implant to be used may be of standardshapes and sizes.

Implant Body

The implant body 27 is in one embodiment substantially plate shaped,meaning that the shortest distance (represented by 24 in FIG. 3a )crossing the surface 15 of the implant body 27 is substantially larger,e.g. at least 1.5 times larger than the thickness 14 of the implant body27. By substantially plate shaped is meant that the implant body 27 maybe substantially flat or may have some curvature, preferably a 3Dcurvature of the articulate surface 15. The plate shaped implant body 27has a cross-section 81 that substantially corresponds to the area of thedamaged cartilage, see FIGS. 3c-f and 13a-l implant 10, with fourexemplifying cross-sectional views, 81 a-d. The articulate surface 15 ofthe plate shaped implant body 27 may have a curvature that substantiallycorresponds to the curvature of a healthy articulating surface at thesite of diseased cartilage. The curvature may for instance correspond toa simulated healthy cartilage reconstructed from an image taken with MRIimage or the CT-scanning of the damaged cartilage surface of the joint.Once the implant 10 is placed in the joint there will be a surface withno parts of the implant pointing up from or down below the surroundingcartilage—the implant is incorporated to give a smooth surface.

The size and the shape of the implant body 27 may be individuallyadapted, or may be chosen from a set of standards, dependent on the sizeof cartilage damage and location of the cartilage damage. The area andshape of the implant can be decided by the surgeon himself or be chosenfrom predetermined shapes. For instance the cross-section of the implantbody 27 may have a circular or roughly circular, oval, triangular,square or irregular shape, preferably a shape without sharp edges (seee.g. FIGS. 3c-f and 13a -l, implant 10). The size of the implant 10 mayalso vary. The area of the articulate surface 15 of the implant variesin different realizations of the disclosure between 0.5 cm² and 20 cm²,between 0.5 cm² and 15 cm², between 0.5 cm² and 10 cm², between 1 cm²and 5 cm² or preferably between about 0.5 cm² and 5 cm².

In general, small implants are preferred since they have a smallerimpact on the joint at the site of incision and are also more easilyimplanted using arthroscopy or smaller open surgical procedures. Theprimary factor for determining the size of the implant is however thenature of the lesion to be repaired.

The articulate surface 15 of the implant body 27, and the core of theimplant body 27, comprises a biocompatible metal, metal alloy orceramic. More specifically it can comprise any metal or metal alloy usedfor structural applications in the human or animal body, such asstainless steel, cobalt-based alloys, chrome-based alloys,titanium-based alloys, pure titanium, zirconium-based alloys, tantalum,niobium and precious metals and their alloys. If a ceramic is used asthe biocompatible material, it can be a biocompatible ceramic such asaluminium oxide, silicon nitride or yttria-stabilized zirconia.Preferably the articulate surface 15 comprises a cobalt chromium alloy(CoCr) or stainless steel, diamond-like carbon or a ceramic. Thearticulate surface 15 and the core of the implant body 27 may compriseone or several different materials.

The articulate surface 15 may also be further surface treated in orderto e.g. achieve an even more durable surface or a surface with a lowerfriction coefficient. Such treatments may include, for example,polishing, heat treatment, precipitation hardening or depositing asuitable surface coating.

The Bone Contact Surface

The implant body 27 has a bone contact surface 21, configured to face orcontact the bone structure of the joint. In one embodiment the bonecontact surface 21 comprises a biocompatible metal, metal alloy orceramic, such as any of the metals, metal alloys or ceramic describedabove for the articulate surface 15. Preferably the bone contact surface21 comprises a cobalt chromium based alloy (CoCr), a titanium alloy,titanium or stainless steel.

In one embodiment the bone contact surface 21 comprises, or in onespecific embodiment is coated with, a bioactive material. In analternative embodiment of the disclosure the bone contact surface doesnot comprise a bioactive material and/or is uncoated.

The bioactive material of the bone contact surface, if present,preferably stimulates bone to grow into or onto the implant surface.Several bioactive materials that have a stimulating effect on bonegrowth are known and have been used to promote adherence betweenimplants and bone. Examples of such prior art bioactive materialsinclude bioactive glass, bioactive ceramics and biomolecules such ascollagens, fibronectin, osteonectin and various growth factors. Acommonly used bioactive material in the field of implant technology isthe bioactive ceramic hydroxyapatite (HA), chemical formulaCa₁₀(PO₄)₆(OH)₂. HA is the major mineral constituent of bone and is ableto slowly bond with bone in vivo. HA coatings have been developed formedical implants to promote bone attachment. Another bioactive materialcommonly used in prior art is bioactive glass. Bioactive glasses,generally comprising SiO₂, CaSiO₃, P₂O₅, Na₂O and/or CaO and possiblyother metal oxides or fluorides, are able to stimulate bone growthfaster than HA.

The bioactive materials described above have an anabolic effect on thebone i.e. stimulates bone growth. The fixation of the implant can alsobe improved by decreasing the catabolic processes i.e. decrease theamount of bone resorption next to the implant. The bone contact surface21 and/or the extending post can also be modified with bisphosphonates.Bisphosphonates are substances that decrease the catabolic process ofbone and binds readily to HA. One way to bind the bisphosphonate to thesurface is by coating it with HA, which it readily binds to. The implantcan also simply be immersed in a bisphosphonate solution or linked withsome other biocompatible molecule e.g. carbodiimides,N-hydroxysuccinimide (NHS)-esters, fibrinogen, collagen etc.

In one embodiment the bone contact surface 21 is coated with a doublecoating. Such double coating may for instance comprise an inner coatingcomprising titanium (Ti). The second, outer coating, that is configuredto contact the cartilage and or bone, is preferably a hydroxyapatiteand/or beta tricalcium phosphate (TCP) coating containing more than 95%hydroxyapatite or 95-99.5% hydroxyapatite. By this design even morelong-term fixation of the implant is achieved, since bone in- oron-growth to the implant is further stimulated by the titanium, even ifthe more brittle hyroxyapatite would eventually shed/dissolve.

The bone contact surface may also be further modified with fluorocompounds or acid etching to enhance the bioactivity and theosseointegration of the surface. Another method to facilitateosseointegration is blasting of the bone contact surface.

The Extending Post

The implant replaces an area of damaged cartilage in an articulatingsurface of a joint. Before the implant is placed in the desiredposition, the damaged cartilage is removed and also a part of the bonebeneath. Furthermore, a hole can be drilled to fit the implantstructure. One or several extending posts or rod-parts 23 of the implant10 (see FIGS. 3a-b ), may be used for securing the implant 10 in thedrilled hole of the bone. The length of the extending post 23, extendingfrom the bone contact surface 21, is adjusted to a length needed tosecure the implant 10 in the bone. The extending post 23 is intended togive a primary fixation of the implant 10; it provides mechanicalattachment of the implant 10 to the bone in immediate connection withthe surgical operation.

The position of the extending post 23 on the bone contact surface 21 canbe anywhere on the bone contact surface 21 or the extending post 23 mayhave a central position.

The extending post 23 has a physical structure in the form of forexample a cylinder or other shapes such as one or more of a small screw,peg, keel, barb or the like.

The extending post 23 can in one embodiment of the disclosure be coatedwith a bioactive material, for example a bone stimulating material withsingle or double coatings and/or, a substance inhibiting bone resorptionsuch as described for the bone contact surface 21 above. The surface ofthe extending post can also be further modified using e.g. fluorocompounds or acid etching or blasting, to enhance osseointegration ofthe surface.

In another embodiment of the disclosure the extending post 23 isuncoated and the extending post may comprise e.g. a metal, metal alloyor ceramic material, such as the metal, metal alloys or ceramicmaterials described for the articulate surface 15 above.

In one embodiment, as exemplified in FIGS. 3a -b, the extending post 23has a positioning part 25, where the positioning part 25 is locateddistal to the plate shaped implant body 27. The longitudinal symmetryaxes of the first part of the extending post 23 and the positioning part25 coincide. The diameter of the positioning part 25 is smaller than thediameter of the first part of the extending post 23.

In one embodiment the implant has a surface spreading corresponding totwo overlapping circles, and the implant has one extending post. Inanother embodiment the implant has a surface spreading corresponding totwo overlapping circles, and the implant has two extending posts.

Grafted Plug or Artificial Plug

In an alternative embodiment the surgical kit of the present disclosuremay be used for mosaicplasty or osteochondral autograft transfer (OATS).In such case the implant to be used with the surgical kit does not havea plate shaped implant body with extending post, but rather is a graftedplug taken from healthy bone and cartilage, see FIGS. 4a -b. Grafts canalso be obtained from donors (so called allografts). Artificial plugs,having the same general shape as a grafted plug but being made of anartificial material (see below), can also be applied. FIG. 4a shows agrafted plug 600 in the form of a bone and cartilage plug, such as aosteochondral plug, that has been harvested from a nonbearing part of ajoint. The implant body 627 of the grafted plug 600 has a cylindrical toa substantially cylindrical form. By cylindrical to a substantiallycylindrical form is meant a form or shape having parallel side walls,and having a cross-sectional profile 81 that is preferably circular orroughly circular but that may also have any other shape, including oval,triangular, square or irregular shape, preferably a shape without sharpedges, see exemplifying cross-sections 81 a-d in FIGS. 4c -f. At theupper part of the grafted plug 600 there is healthy cartilage 606 fromthe site of harvest, while the lower portion of the grafted plug 600comprises bone tissue.

The grafted plug 600 may be further reshaped after harvesting by using asharpener tool, see FIG. 4b . The sharpener tool may be constructed as apencil sharpener, with a sharp blade, but which may be used to adjustthe shape and/or the length of the bone part of the grafted plug 600, inorder to arrange such that several plugs may fit together in an area ofcartilage damage. The implant body 627, i.e. the upper part of thesharpened grafted plug 600, still has a cylindrical form, as definedabove, i.e. with parallel side walls and a cross-sectional profile 81that can have various shapes.

In another embodiment the plug used may be an artificial plug made of anartificial material such as synthetic polymer scaffolds, e.g.polylactide-co-glycolid, calcium sulfate, polycarbonate polyurethane orpolyglycolide fibers or synthetic calcium. Such artificial plugs havethe same geometrical shapes as the grafted plug 600 described above.Importantly for the present disclosure the artificial plug, like graftedplug 600, has an implant body 627 with a cylindrical form, that is aform or shape with parallel side walls and with a cross-sectionalprofile 81 that is preferably circular or roughly circular, but that mayalso have any other shape, including oval, triangular, square orirregular shape, preferably a shape without sharp edges.

In embodiments, a grafted plug 600 or an artificial plug has across-sectional area that is between 0.5 cm² and 5 cm², between 0.5 cm²and 3 cm², or preferably between about 0.5 cm² and 2 cm² at itscylindrical portion. It has a length 710 that is between 1 and 4 cm, orbetween 1.5 and 3 cm. The cross-sectional diameter at the cylindricalportion may for example be 0.1-1 cm.

FIGS. 4g-h show a cartilage damage site repaired using mosaic repairtechnique, FIG. 4g from a cross-sectional side view of the joint, andFIG. 4h from above. Several grafted plugs 600 have been inserted at thesite of damaged or diseased cartilage, to form a mosaic pattern. FIG. 4halso shows that grafted plugs 600 have been harvested from the healthypart of the joint (right hand side of the figure).

According to an embodiment of the present disclosure the amounts ofplugs and also the size and shape of the healthy cartilage and boneplugs are selected depending on the shape and size of the injury.

The Set of Tools

The set of tools comprises a guide base 12, to which a guide body 13with a guide channel 54 is attached, see FIGS. 5a -7. It may alsocomprise a selection of insert tools, for use when mounting an implant10, a grafted plug 600 or an artificial plug to the implant site, seeFIGS. 2 and 8-11 b. The insert tools are in operation inserted in theguide channel 54 of the guide body 13 and fit in the guide channel 54,with a slight tolerance to allow a sliding movement of the insert toolin the guide channel 54. The cross-sectional profile, and thus thecircumferential shape of the insert tools, corresponds to the chosencross-section 81 of the implant body 27, 627 of the implant 10, graftedplug 600 or artificial plug, in size and shape (see FIGS. 13a-l ). Theinsert tools are in different embodiments of the disclosure provided inthe form of for example a cartilage cutting tool, a punch, a drill, adrill guide, a bone cutting tool, a reamer guide and/or a hammer tool.Some insert tools are used together with further tools such as a drillbit and/or a reamer bit. An exemplifying set of insert tools will bedescribed herein. The surgical kit of the disclosure may further be usedwith other insert tools, such as insert tools disclosed in PCTapplication PCT/EP2011/058473 or European patent application 11163405.1.

Guide Base, Guide Body and Guide Insert

FIG. 6 shows an exemplifying embodiment of a surgical kit of thedisclosure, for use in a knee joint. FIG. 7 shows an exemplifyingembodiment of a surgical kit of the disclosure, for use in a toe joint.The modular surgical kit comprises a guide base 12 that is attached to aguide body 13. FIGS. 5a-d show the guide base 12 in more detail.

Two embodiments of a guide base 12 for use in a knee joint are shown inFIGS. 5a -b, and one embodiment of a guide base 12 for use in a toejoint is shown in FIGS. 5c -d. In FIGS. 5b and 5d the guide base 12 isplaced on the femoral bone 141 of the knee joint and a falangeal jointbone 142 of a toe respectively. The guide base 12 comprises apositioning body 11 and a guide hole 53, which may alternatively bedenoted guide recess or guide opening or similar, through saidpositioning body 11. The positioning body 11 has a cartilage contactsurface 50 that has a shape and contour that is designed to correspondto and to fit the contour of the cartilage or the subchondral bone inthe joint in a predetermined area surrounding the site of diseasedcartilage. The cartilage contact surface 50 may be adapted to fit to thejoint of an average patient or may be adapted, i.e. custom made, for anindividual patient. The positioning body 11 also has a top surface 52facing the opposite direction compared to the cartilage contactingsurface 50.

The guide hole 53 has a muzzle 29 on the cartilage contact surface 50,at a position of the positioning body 11 that corresponds to the site ofthe diseased cartilage, i.e. the site of implantation. In one embodimentthe guide hole 53 has a cross-sectional profile that is designed tocorrespond to the cross-section 81 of the implant body 27, 627 of theimplant 10, grafted plug 600 or artificial plug to be implanted. Inanother embodiment the guide hole 53 has a cross-section that isslightly larger than the cross-section 81 of the implant body 27, 627.In a further embodiment the cross-sectional profile of the guide hole 53need not correspond to the cross-section 81 of the implant body 27, 627.Where the cross-sectional profile of the guide hole 53 is different fromthe cross-section 81 of the implant body 27, 627, correspondence ormatching to the cross-section 81 of the implant body 27, 627 is providedby the cross-sectional profile of the guide channel 54 of the guide body13 only (see below).

An embodiment of a guide body 13 is shown in FIGS. 6 and 7. The guidebody 13 has a guide channel 54 that extends through the guide body 13.The outer shape and design of the guide body 13 may vary, as isschematically illustrated by a circular design 13 a and a square design13 b in FIGS. 13a-c (implant 10 and guide body 13 a, 13 b seen fromabove). The guide channel 54 of the guide body 13, however, has an innercross-sectional profile (see FIG. 13a-l ) that is designed to correspondto the cross-section 81 of the implant body 27, 627. In other words, theimplant body 27, 627 fits the guide channel 54, with a slight toleranceto allow a sliding movement of the implant in the guide channel 54.

In an alternative embodiment the guide body 13 has a guide channel thathas a cross-sectional profile which is larger than the cross-sectionalprofile 81 of the implant body 27, 627. In this case the guide channel54 that is designed to correspond to the cross-section 81 of the implantbody 27, 627 is instead provided by a guide insert 8 (see FIGS. 6 and 7,and top view in FIG. 13a-l ). The guide insert 8 is designed to haveouter proportions to make it fit in the guide channel of the guide body13. Its guide channel 54 is designed to have an inner cross-sectionalprofile that corresponds to the cross-section 81 of the implant body 27,627. In other words, the implant body 27, 627 fits the guide channel 54,with a slight tolerance to allow a sliding movement of the implant inthe guide channel 54. In this way the guide insert 8 works as anadapter, such that a guide body 13 with a guide channel of a certainsize might be used for implantation of implants of various sizes, by useof guide inserts 8 with varying guide channels 54 that fit implants ofcorresponding varying sizes.

The height 31 of the guide channel 54 must be sufficiently long to givesupport to the tools used inside the guide body 13. The height 31 of theguide channel 54 is preferably also sufficiently high to be easilyaccessible for the surgeon during surgery. In one embodiment, the top ofthe guide channel 54 is designed to project above the tissue surroundingthe surgery cut when the guide tool is placed on the cartilage in ajoint during surgery. The height 31 is preferably higher than thethickness of the surrounding tissue. In this way, the opening of theguide channel 54 is easy to access for the surgeon. The height 31 of theguide channel 54 is between 1 and 10 cm, preferably 3-10 cm and alwayssufficiently high to ensure stabilization of the tools that are to beinserted into the guide channel 54.

FIG. 8 shows an embodiment of a guide body 13, for use in mosaicplastyor OATS surgery. The guide body 13 comprises at least two guide channels54. Each of the guide channels 54 is designed to have a cross-sectionalprofile that corresponds the cross-section 81 of an implant body 627 ofa grafted plug 600 or an artificial plug. The at least two guidechannels 54 may have cross-sectional profiles that are identical.Alternatively their cross-sectional profiles may be different in shapeand/or size/area, depending on the cross-sectional profile 81 of therespective grafted plugs 600 or artificial plugs that are to beimplanted. Each of the guide channels 54 may also be arranged in theguide body 13 at different angles, depending on the angle in which therespective plugs are to be implanted.

The guide body 13 may be provided with an inspection window 39, i.e. awindow or hole through the side of the guide body 13, into the guidechannel 54, see FIGS. 6 and 7. The inspection window 39 facilitatesinspection of the site of implantation during surgery, also when theguide body 13 is attached to the guide base 12, see FIGS. 14c -h.

The guide base 12 comprises means for releasable attachment 47 to theguide body 13, see FIGS. 5a and b-c and FIG. 6. Such means 47 isarranged such that when the guide body 13 is attached to the guide base12 the guide body 13 extends from the top surface 52 of the guide base12. Such means for releasable attachment 47 is also arranged such that,when attached, the guide channel 54 is positioned in relation to thepositioning body 11 such that its muzzle 32 emanates at a sitecorresponding to the site of implantation into the bone, which is alsoat the site of the guide hole 53. The angle of the guide hole 53 in thepositioning body 11 and the arrangement of the releasable attachmentmeans 47 also determine the angle of the guide channel(s) 54 in relationto the positioning body 11 and implantation site. The guide hole 53and/or the means for releasable attachment 47 are arranged such that,when the guide body 13 is attached to the guide base 12, the angle ofthe guide channel(s) 54 will correspond to the angle in which theimplant 10, grafted plug(s) 600 or artificial plug(s) is/are to beinserted. For small implants 10 the angle of implantation, and thus ofthe guide channel 54, is most often perpendicular to a tangential planeof the site of implantation. For implants 600 used in mosaicplasty orOATS surgery the angle of implantation of the respective plugs, and thusof the respective guide channels 54, may vary.

In one embodiment the cross-sectional profile of the guide hole 53 andthe guide channel 54 correspond and the guide hole 53 and the guidechannel 54 are aligned. That is, the symmetry axis of the guide hole 53and the longitudinal symmetry axis of the guide channel 54 approximatelycoincide. The cross-sectional profile of the guide hole 53 and of theguide channel 54 may in another embodiment be different. Thecross-section of the guide hole 53 must however be at least as big asthe cross-section of the guide channel 54, the cross-section of theguide channel 54 must correspond to the cross-section 81 of the implantbody 27, 627 and the muzzle 32 of the guide channel 54 must emanate at asite corresponding to the site of implantation, when the guide body 13is attached to the guide base 12.

The means for releasable attachment 47 may be provided by a snap fitfunction between the guide base 12 and the guide body 13, and/or by theguide hole 53, or part of the guide hole 53, and the lower part of theguide body 13 being provided with matching threads and/or bayonet mountand/or other form fitting mechanisms. Other releasable attachmentmechanisms are however also conceivable. The guide tool can also bewithout a releasable attachment mechanism.

The guide base 12 is easy to place due to the precise fit of thepositioning body 11 on the cartilage surface. The guide base 12 isdesigned to be inserted in a lesion which is as small as possible to beable to repair the specific cartilage damage. The size and shape ofcartilage contact surface 50 of the guide base 12 is determineddepending on the size and shape of the damaged cartilage and alsodepending on the position of the cartilage damage in the joint. The sizeand shape of the surface 50 and the positioning body 12 is aconsideration between the following aspects; minimize surgery lesion,maximize stability for the guide base 12, anatomic limitations on thesite of the injury, and that not all cartilage surfaces in a joint canbe used for placement of the guide tool. A large spread of the cartilagecontact surface 50 is to prefer to get good stability of the guide tool,however, a large surface area of the surface 50 may also lead to a largesurgical intervention and this is undesired. Thus the size of thecartilage contact surface 50 and of the positioning body 11 isdetermined by a balance between the desire to achieve good positioningstability and small surgical operations. Also, the cartilage contactsurface 50 does not need to have a continuous, regular shape, but mayhave an irregular shape, as long as it gives adequate support and stablepositioning of the guide base 12.

When designing the guide tool, the cartilage contact surface 50 can bedesigned to cover three points (see FIG. 5b , points 40, 42, 44 for anexample) distributed over the cartilage surface of the joint where theimplant is to be inserted. The points are chosen to give maximum supportand positional stability for the positioning body 11 and thus thesepoints, either decided and identified by the surgeon or automaticallyidentified by design software, serve as the ground when designing thesurface 50 of the guide base 12. The cartilage contact surface 50 canalso be formed such that it uses the curvature in the cartilage surfacein a joint for stability. For example, in a knee joint, the condyles areseparated from each other by a shallow depression, the posteriorintercondyloid fossa, this curvature together with the medial epicondylesurface can be used to give the cartilage contact surface 50 a stabileattachment to the cartilage surface in a knee joint. The surface is inone embodiment a continuous surface covering a selected area surroundingthe cartilage damage. In another embodiment the cartilage contactsurface is distributed over a plurality of points, preferably three ormore of separated contact points. The cartilage contact surface does notneed to be a continuous, regular surface, but preferably has at leastthree points exemplified by 40, 42 and 44 for stability.

Optionally the cartilage contacting surface 50 can be further stabilizedby attachment with nails, rivets or similar attachment means 48 to thebone surrounding the cartilage in a joint (see FIG. 5b ). Thisadditional attachment with rivets or the like gives additional supportand stability and also gives the possibility to keep the cartilagecontact surface as small as possible. The position of the rivets may bepredetermined and marked out on the surface 50 by premade drill holes.

In an alternative embodiment the positioning body 11 may be arrangedwith attachment means 9 for attachment of adaptors 17, pins and possiblyother devices to the guide base 12, see FIGS. 5a, c and d, 6, 7 and 14a-b. Such attachment means 9 may for example connect to the adaptor 17,pin or other device through a snap fit function, thread function or anyother form fitting function. The adaptors 17 shown in FIGS. 6, 7 and 14b have holes or bores that can receive pins, nails, rivets or similarmeans 48 in order to secure the attachment of the guide base 12 to thebone as described above. The elongated form of the adapters 17 allowsuch pins or similar means to be inserted into the bone at a distancefrom the site of implantation. Adaptors of the embodiment shown in FIG.14b also have a shape, i.e. both bent and somewhat elongated, such thatthe pin holes will be both lifted or elevated from the joint surface andsituated at a distance from the site of implantation. This shape isadvantageous since it will be easier to keep the surface of the jointfree of waste and debris from the implantation wound and surroundingsand since it will be possible to insert the pins more straight fromabove. Inserting the pins from at an angle from the side often meansthan the skin around the site of incision has to be more split open andthus that the wound will be bigger. This is thus avoided when usingadaptors as seen in FIG. 14 b.

As stated above, the size and shape of the positioning body 11 of theguide base 12 are determined in order to minimize the surgicalintervention while also maximizing the stability of the guide base 12 inthe joint. While designing the guide base 12, e.g. by use of X-ray, MRor CT images from the patient it is normally desired to have apositioning body that is as large as possible, in order to ensuremaximum stability and proper positioning of the guide base 12 in thejoint. However, not all facts on the patient's joint may be knownthrough the X-ray, MR or CT images, and thus the surgeon may want toadjust the positioning body 11 during surgery. For example, osteophytesmight have formed in the joint and are often difficult to identify inthe imaging procedures. Also, the surgeon might find during surgery thatthe shape of the guide base 12 requires an unnecessarily large incisionto be able to insert the guide base 12 into the joint. In order tofacilitate adaptation of the size and shape of the guide base 12 duringsurgery, the positioning body may be arranged with breakage means 57that enable easy removal of part(s) of the positioning body 11 bytearing, fracturing or similar ways of breakage, see e.g. FIG. 5a . Suchbreakage means 57 may for example be provided through grooves, slots orperforations or other weakening of the structure.

The guide base 12 with guide body 13 aid with exact precision removal ofa volume of cartilage and subchondral bone and also guide the placementof the implant 10, the grafted plug 600 or the artificial plug in forexample a knee. Placement of the guide base 12 on the cartilage surfaceof a knee or a toe can be seen in FIGS. 5b and 5d . The use of the guidebase 12 and guide body 13 is further explained below in connection toFIGS. 14a -t.

The guide base 12 and the guide body 13 are manufactured using suitablematerials that are approved for use in medical procedures, e. g. aceramic, plastic, metal, metal alloy or alumina material, or acombination. The guide base 12, especially the cartilage contact surface50, is also preferably made of a material that is smooth, even and/orhas low friction, in order to lessen the risk of wear and damage to thecartilage on which it is to be placed. Such materials include e.g.metals ceramics and polymers such as acrylonitrile butadiene styrene(ABS). The used materials may further be polished. In a preferredembodiment the guide base 12 is made of a plastic material, such aspolyamide or epoxy, while the guide body 13 is made of a metal materialor stainless steel. The plastic material of the guide base 12 is easy tomanufacture, e.g. using selective laser sintering (SLS) orstereolithography (SLA) technologies, also when adapted for a specificpatient. It is also gentle to the cartilage surface of the joint. Themetallic material of the guide body 13 on the other hand, provides awear resistant material that is to be in contact with the insert tools,thus minimizing the risk of generating wear debris from the guide bodyfor example during drilling. It is also autoclavable and thus reusable.In one embodiment the guide base 12 is adapted to a specific patient, byhaving a cartilage contact surface 50 and a positioning body 11 that aredesigned to match the cartilage surface and the shape of the joint ofthe patient. In one embodiment the guide body 13 is made in a number ofstandard shapes and sizes, matching corresponding shapes and sizes of aset of standard implants 10, while in another embodiment the guide body13, as well as the implant 10, is also adapted to the specific patient.

Drill Adjustment Device

In a preferred embodiment the surgical kit further comprises a drilladjustment device 16 as for example illustrated in FIGS. 2, 6 and 7. Thedrill adjustment device 16 of the embodiment shown is arranged forattachment to the top of the guide body 13, e.g. by threads. The drilladjustment device 16 is further arranged such that it may be used toadjust the length of the guide channel 54. The length 31 of the guidechannel 54 determines the depth of drilling and cutting of the bone inthe joint, as will be described further below. Thus, by being able toadjust the length 31 of the guide channel the surgeon is also able toadjust the depth of drilling and cutting into the bone. The length 31 ofthe guide channel may be varied since the guide body 13 and the drilladjustment device 16 are able to move in relation to one another whenattached. This may for example be achieved by corresponding threading ofthe guide body 13 and drill adjustment device. Further, the guide body13 and/or drill adjustment device may be arranged such that the length31 of the guide channel may be varied at certain intervals, e.g. at 200μm intervals, or any other desired interval. This may for instance beachieved by arranging the guide body 13 and/or the drill adjustmentdevice 16 such that they are able to move in relation to one another atcertain intervals. For example, the threading may be arranged such thatthe guide body 13 and drill adjustment device 16 may be turned inrelation to one another at preset intervals, and that they are locked inrelation to each other or prone to hook each other at those intervals.This is readily implemented by a snap fit function.

The drill adjustment device 16 may be used by the surgeon to adjust thedepth of drilling, e.g. by increasing the drill depth in steps at thepreset intervals. The drill adjustment device is advantageously usedtogether with an implant dummy 36, as described below, to make sure thatthe drill depth in the bone matches the height 14 of the implant body27. This ensures that the articulate surface 15 of the implant 10 willbe in line with the surrounding cartilage at the site of implantationonce implanted. For further description of how the drill adjustmentdevice 16 is used during surgery, see below in connection with FIGS. 14j-p.

An alternative embodiment of a drill depth adjustment tool that may beused is disclosed in PCT application PCT/EP2011/058473, see e.g. pages20-21 of the description and FIGS. 12-14. Another way to adjust thedrill depth is also to have an adjustable depth gauge on the drillingtool, see below.

Cartilage Cutting Tool

The cartilage cutting tool 3 is a tool which is used to cut thecartilage in the joint around the area of damaged cartilage to preparefor the insertion of the implant. The cartilage cutting tool may forexample be a cartilage cutter 3, as shown in FIGS. 2 and 9, a punch or acartilage cut drill. It is used inside the guide channel 54 of the guidebody 13 and fits in the guide channel 54, with a slight tolerance toallow a sliding movement of the cartilage cutting tool 3 in the guidechannel 54 (see FIG. 13a-l ). The cartilage cutting tool 3 preferablycuts the cartilage so that the cut edges of the cartilage are sharp andsmooth. These sharp and smooth edges are of great importance when theimplant is placed into the prepared recess in the cartilage and bone. Ahole in the cartilage which is cut (or punched or drilled) with thecartilage cutting tool 3 according to the disclosure ends up with aprecise fit of the implant into the prepared cartilage since thecartilage cutting tool allows for an exact, precise cut. The recess inthe cartilage, made by the cartilage cutting tool 3 always correspondsto the chosen cross-section 81 of the implant body 27 in size and shape.

In one exemplifying embodiment of the disclosure the cartilage cuttingtool is a cartilage cutter 3. The cartilage cutter 3 is used to cut thecartilage in the joint around the area of damaged cartilage to preparefor the insertion of the implant with a cutting technique.

The cartilage cutter 3 has a handle 3 a, a cartilage cutter body 3 b anda cutting blade with sharp cutting edges 3 c. The cartilage cutter body3 b has a cross-sectional profile that is designed to correspond to theinner cross-sectional profile of the guide channel 54 with a toleranceenabling the cartilage cutter body 3 b to slide within the guide channel54 (see FIG. 13a-l ). Also, the cross-sectional profile is designed tocorrespond to the cross-section of the implant. Thus, the cartilagecutter body 3 b fits the inside of the guide channel 54, see FIG. 13,with a slight tolerance to allow a sliding movement of the cartilagecutter in the guide channel 54. The fit ensures the correct, desiredplacement of the cartilage cutting edges 3 c on the cartilage surfaceand thus the precise removal of the damaged cartilage area.

The cartilage cutter 3 of the embodiment shown in FIG. 9 has a cartilagecutter body 3 b comprising a circular cutting blade that has been cut atan angle that is not perpendicular to the length of the cutter body 3 b.This creates an oval cutting edge 3 c with a pointy appearance, furtherincreasing the sharpness of the cartilage cutter 3. The cutting edge 3 cis arranged to cut the cartilage in a shape corresponding to thecross-sectional profile 81 of the implant body 27.

The material of the cartilage cutter body 3 b is chosen from materialswhich can give the cartilage cutter 3 sharp cutting edges 3 c. Thematerial also needs to be stable in order to withstand the pressure whenthe cartilage cutter 3 is pushed into the cartilage. Examples of suchmaterials are metals such as stainless steel or ceramic material or aplastic material or a hard coated material, preferably stainless steel.

The cutter body 3 b may be permanently attached to the handle 3 a, ormay, more preferably, be removably attached to the handle 3 a, such thatthe handle 3 a is reusable while the cutter body 3 b is be exchangeable(see FIG. 9).

The cartilage cutter 3 may be provided with a safety stop 4. The safetystop 4 has a cross-sectional profile that is larger than the grosssectional profile of the guide channel 54. In case the cutter would riskdigging too deep into the bone the safety stop 4 will be stopped againstthe top of the guide body 13 and/or drill adjustment device 16, thuspreventing the cartilage cutter 3 to be pushed deeper into the bone.This could happen e.g. when the patient suffers from osteoporosis. Thedistance between the tip of the cutting edge 3 c and the safety stop 4,and the relation between that distance and the length 31 of the guidechannel 54, will determine the depth that the cartilage cutter 3 isallowed to go into the cartilage and/or bone. The safety stop 4 may bearranged such that that distance is adjustable.

In alternative exemplifying embodiments of the disclosure the surgicalkit may comprise a cartilage cutting tool in form of a punch, to punchout the cartilage, or in form of a cartilage cut drill, to cut thecartilage and also cut/carve/drill the underlying bone, as are disclosedin PCT application PCT/EP2011/058473, see pages 17-18 and FIGS. 2, 5 a-band 10. The punch may for instance be advantageous when the implant 10has a non-circular shape and/or the extending post 23 is not centrallyplaced in relation to the implant body 27.

In alternative exemplifying embodiments of the disclosure there is nocartilage cutting tool in the surgical kit, but the cartilage cuttingfunction is incorporated in the drill and bone remover.

Drill and Bone Remover

In one embodiment of the present disclosure the surgical kit comprises adrill and bone remover 2 (see FIGS. 2 and 10) that is used to drill ahole in the bone at the site of cartilage damage, for fastening of theextending post 23 of the implant 10 in the bone tissue, andsimultaneously create a recess in the bone tissue at the site where theimplant body 27 is to be received. The drill and bone remover 2comprises a drill and bone remover body 20, a central drill 22 and abone remover 26, as shown in FIG. 10. The central drill 22 extends fromthe centre of the drill and bone remover body 20, i.e. corresponding tothe position of a centrally placed extending post 23 on an implant 10having a circular implant body 27. The diameter of the central drill 22is the same as, or slightly smaller than, the diameter of the extendingpost 23 of the implant 10 that is to be implanted. The bone remover 26has a cutting edge that is placed peripherally around the central drill22. The diameter of the bone remover 26 is the same as, or slightlysmaller than, the diameter of the implant body 27 of the implant 10 thatis to be implanted, thus creating a recess that matches the implantbody, in which the implant body can be received. The cutting edge of thebone remover 26 is hard enough for cutting or carving bone. It may bemade of materials such as stainless steel.

The drill and bone remover body 20 is designed to fit the inside of theguide channel 54 of the guide body 13, with a slight tolerance to allowa sliding movement of the drill and bone remover 2 in the guide channel54. In other words, the cross-sectional profile of the drill and boneremover body 20 matches the cross-sectional profile of the guide channel54 as well as the of the implant 10, see FIGS. 13a -l. The fit ensuresthe correct, desired placement of the drill and bone remover 2 on thecartilage surface and thus ensures the precise direction and placementof the drill hole for the extending post 23, as well as the recess forthe implant body 27, in the bone.

The drill and bone remover 2 is also equipped with a depth gauge 7. Thedepth gauge 7 of the drill and bone remover determines the depth of thecreated drill hole as well as the recess for the implant body 27. Thedepth gauge 7 has a cross-sectional profile that is larger than thecross sectional profile of the guide channel 54. The depth gauge 7 will,during the surgical procedure, rest against the top of the guide body 13and/or drill adjustment device 16, thus preventing the drill and boneremover 2 to drill/carve/cut deeper into the bone. The distance betweenthe tip of the cutting edge of the cutter 2 and the depth gauge 7, andthe relation between that distance and the length 31 of the guidechannel 54, will determine the depth that the is allowed to go into thecartilage and/or bone. The depth gauge 7 may be arranged such that thatdistance is adjustable. In a more preferred embodiment the distance isfixed and instead the drill/cut/carve depth is adjusted by adjusting thelength 31 through the drill adjustment device 16.

See FIG. 14g-p for a demonstration of how the drill and bone remover 2is used and how the drill depth is adjusted using the drill adjustmentdevice 16.

In alternative exemplifying embodiments of the disclosure the surgicalkit may, instead of an integrated drill and bone remover, comprise adrill bit for drilling the hole for the extending post and a reamer forremoving bone where the implant body is to be received in the bone. Suchembodiments may also comprise a drill guide and/or a reamer guide.Examples have been disclosed in PCT application PCT/EP2011/058473, seepages 18-20 and 21 of the description and FIGS. 6-7. Such tools may forinstance be used when the implant 10 has a non-circular shape and/or theextending post 23 is not centrally placed in relation to the implantbody 27.

Implant Dummy

The implant dummy 36, see FIGS. 2 and 11 a-b, is used, possibly togetherwith a dummy reference 37, to make sure that the cut, carved or drilledrecess in the bone that is to receive the implant body 27, is deepenough to fit the implant in a desired way, such as the implant beinginserted slightly recessed compared to the surrounding articularsurface. This is very important, since the articulate surface 15 of theimplant 10 must not project over the surface of the surroundingcartilage tissue. If it would, it could cause a lot of damage to thesurrounding cartilage and to the cartilage on the opposite side of thejoint. Preferably the articulate surface 15 should form a continuoussurface with the surrounding cartilage, or the implant should be placedslightly below the surface of the surrounding cartilage. The checking ofthe recess depth is difficult or impossible to do with the implant 10itself, since the implant 10, e.g. with its extending post 23, isdesigned to be fixed in the bone once inserted, and thus is difficult orimpossible to remove. The implant dummy, on the other hand, is designedfor easy removal from the recess once the recess depth has been checked.

The implant dummy 36, see FIG. 11 b, has an implant element 41 that isdesigned to match the implant body 27. The lower surface 41 a of theimplant element 41 is a replica of the bone contact surface 21 of theimplant that is to be implanted. That is, if the implant 10 and bonecontact surface 21 is custom made for the specific patient, the implantelement 41 and its lower surface 41 a will also be custom made and thelower surface 41 a be a replica of the bone contact surface 21. Thecross-sectional profile of the implant element 41 corresponds to thecross-sectional surface 82 of the implant body, or is slightly smallerin order to ensure easy removal of the implant dummy from the recess.

The implant dummy 36 also has a top surface 43. The distance 46 betweenthe lower surface 41 a of the implant element 41 and the top surface 43corresponds to the distance that you get when adding the thickness 14 ofthe implant body 27 (corresponding to the depth of the recess in thebone plus the thickness of the corresponding cartilage), the height ofthe guide hole 53 and/or the length 51 a of the dummy reference 37,taking regard to any overlap between the guide hole 53 and the dummyreference 37 when they are attached. For a demonstration on how therecess depth is checked using the implant dummy 36 together with thedummy reference 37, see below in connection with FIGS. 14j -p. In oneembodiment the thickness 41 b of the implant element 41 is the same asthe thickness 14 of the implant body 10, such that the recess depth canalso be checked directly using the implant element 41 only, i.e. withoutthe dummy reference 37 and top surface 43.

The dummy reference 37, see FIG. 11 a, is arranged to fit to, andpossibly releasably attach to, the guide hole 53 of the guide base 12,see FIGS. 14j -k. It is also arranged to receive the implant dummy 36,by being provided with a channel 58. The cross-sectional profile ofchannel 58 corresponds to the cross-sectional profile of the guidechannel 54. Thus the channel 58 is able to receive the implant dummy 36,and also the implant 10, with a slight tolerance that allows a slidingmovement of the implant dummy 36 in the channel 58, see FIGS. 13a -l,bottom row to the right. The dummy reference 37 and channel 58 has alength 51 a.

To ensure that the implant dummy 36 is placed in a correct orientationin the recess of the bone, i.e. in an orientation that corresponds tothe orientation that the implant 10 is to be inserted in, the topsurface 43 and/or the implant element 41 may be provided with some kindof marking or shape fit element 43 a. A corresponding marking or shapefit element 51 b is then provided also on the dummy reference and/or theguide base 12.

Mandrel

The mandrel 35 (see FIGS. 2 and 12) consists of a solid body and has amandrel surface 35 a that is designed to fit the articulate surface 15of the implant 10, i.e. it has a corresponding cross-sectional profileand preferably also a corresponding, although inverted, curvature. Themandrel may also be designed to fit the inside of the guide channel 54,with a slight tolerance to allow a sliding movement of the hammer tool35 in the guide channel 54. The mandrel 35 is preferably used inside theguide channel 54 to hammer the implant in place, for support and to getthe proper angle, or may alternatively be used without the support fromthe guide channel 54, see FIGS. 14r -s. The height 68 of the mandrel 35is in one embodiment the same height 31 as of the guide channel 54. Forsuch embodiment, once the mandrel 35 is hammered in the same level asthe top of the guide channel, the hammering and thus the placement ofthe implant is finished.

The hammer tool 35 may also be accompanied by a hammer tool adapter 34,see FIG. 12, for facilitating the use of the hammer tool and minimizingthe absorbtion of the shock caused by the hammer tool and/or minimizethe risk of scratching the surface of the implant 10 while hammering. Itis made from a soft material that is gentle to the implant surface, e.g.a rubber or plastic material.

DETAILED DESCRIPTION OF A METHOD FOR IMPLANTING THE IMPLANT USING THESET OF TOOLS

Use of the surgical kit and set of tools disclosed herein will now befurther explained in connection with an exemplifying embodiment shown inFIGS. 14a -t. The example concerns a surgical kit for implantation of asmall implant 10 into a knee joint. The same principles do however applyalso for other joints as well as for mosaicplasty surgery. For thelatter an implant body 13 with more than one guide channel 54 may beused, and the grafted plug 600 may be a selection of bone and cartilageplugs from a healthy part of the joint, or a selection of artificialimplant plugs of various sizes.

1. Localize the area of the injury and determine the desired size andshape of the implant, see FIG. 1. The position and size of the cartilagedamage can be identified by a combination of MRI or CT images or bydGEMRIC technique. The images may then be handled in one or severalspecial surgical planning tool softwares. All or a part of the parts inthe surgical kit may be individually adjusted depending on size ofcartilage damage, location of the cartilage damage and also depending ona simulation of the individual surface appearance without damage.Alternatively an implant from a set of predetermined implants may beselected and the set of tools designed or selected thereafter.

2. The implant 10 and set of tools of the disclosure are manufacturedand sterilized depending on; the size of the implant needed, thelocalization of the injury, the appearance of the cartilage surfaceintended to be replaced. The designs may be based on the MRimages/CT-scanning images from the joint of the person having thecartilage damage, using at least one surgical planning software. Thesurgical planning software may be connected to manufacturing devices,for example a laser printer, a lathe and/or a reamer, and the parts ofthe kit are manufactured using e.g. additive manufacturing, lasersintering techniques, turnery or reaming.

3. A surgical opening is made in the leg tissue depending on thelocalization of the injury and the size of the implant and alsodepending on the size and conformation of the guide tool.

4. The guide base 12 is placed on the surface of the knee cartilage, seeFIG. 14a . The guide base 12 fits due to the fact that it is custom madeto be placed in that particular position. This allows the surgicalprocedure (cartilage and bone removal and insertion of the implant) tobe performed with good accuracy and precision. If necessary the guidetool can be further stabilized with rivets or pins on a part of theguide tool that is in contact with parts of the joint that have nocartilage tissue. The rivets or pins may also be attached by additionaluse of adapters 17 that are first attached to the guide base 12 viaattachment means 9, see FIG. 14 b.

5. The guide body 13 is attached to the guide base 12 via the releasableattachment means 47, see FIGS. 14c -d, or the guide body is alreadyconnected to the guide base. The guide body 13 may further be providedwith a drill adjustment device 16 and/or a drill insert 8 that providesa guide channel 54 of the right shape and size, i.e having across-sectional profile that corresponds to the cross-sectional profile81 of the implant that is to be implanted.

6. When the guide body 13 and the guide base 12 are in place, thecartilage cutting tool, here a cartilage cutter 3, is used to cut out apiece of the cartilage that corresponds to the cross-section 81 of theimplant 10 that is to be implanted (see FIGS. 14e-f ). The cartilagecutter body 3 b fits exactly in the guide channel 54 and thus by turningcan make a hole in the cartilage of the desired size and with precisionto fit the implant size and at the desired position. A depth gauge 4 onthe cartilage cutter 3 can be used in order to help make sure that thecutting is not made too deep. This step is not imperative, if thecutting feature is comprised in the drill and bone remover.

7. The drill and bone remover 2 is then inserted in the guide channel54, see FIGS. 14g -h. When the drill and bone remover 2 isturned/drilled the central drill 22 will give an exact, desiredplacement of a bore in the bone where the extending post 23 of theimplant 10 is to be inserted. The bore is preferably made with a centraldrill 22 having a slightly smaller diameter than the diameter 18 of theextending post 23 of the implant 10 so that when the implant 10 ishammered in place it will be firmly attached in the bone. When the drilland bone remover 2 is turned/drilled the cutting edge of the boneremover 26 will at the same time create a recess in the bone at theexact desired place and of the desired shape to fit the implant body 27of the implant 10. Such recess will have a cross-sectional profile thatis the same as the cross-sectional profile of the drill and bone remover2, i.e. the same as the cross-sectional profile of the implant 10.

8. After the drilling and cutting the drill and bone remover 2 isremoved. The site of implantation can now readily be cleaned from wearand waste from the drilling and cutting, and inspected to see whetherthe desired result has been achieved, preferably with the guide bodystill in place.

9. Now, the implant dummy 36 is used, possibly together with dummyreference 37, to check whether the recess in the bone is deep enough toreceive the implant 10, without the implant 10 projecting over thesurface of the surrounding cartilage and preferably with the implantbeing slightly recessed according to instructions. If used, the dummyreference 37 is first placed and possibly attached to the guide hole 53of the guide base 12, see FIGS. 14j -k. The implant dummy 36 is theninserted to the channel 58 of the dummy reference 37, such that theimplant element 41 is in an orientation corresponding to the orientationin which the implant 10 is to be implanted. This can be ensured e.g. bya marking or shape fit element 43 a on the implant dummy and acorresponding marking or shape fit element 51 b on the dummy referenceand/or the guide base 12.

The implant dummy 36 and dummy reference 37 are arranged such that whenthe depth of the recess in the bone that is to receive the implant body27 is deep enough the top surface 43 of the implant dummy 36 and the topedge of the dummy reference should lie flush or in line with each other,see arrow in FIGS. 14l and 14p . This is achieved by arranging theimplant dummy 36 and the dummy reference 37 such that the distance 46between the lower surface 41 a of the implant element 41 and the topsurface 43 corresponds to the distance that you get when adding thethickness 14 of the implant body 27 (corresponding to the depth of therecess in the bone plus the thickness of the corresponding cartilage),the height of the guide hole 53 and/or the length 51 a of the dummyreference 37, taking regard to any overlap between the guide hole 53 andthe dummy reference 37 when they are attached (see also above).

As is seen by the arrow in FIG. 14l the top surface 43 of the implantdummy 36 and the top edge of the implant reference do not lie flush,i.e. not in line, with each other. Thus, some more drilling/cutting intothe bone should be made. The implant dummy 36 and dummy reference 37 areremoved from the guide base 12 and the guide body 13 with drilladjustment device 16 attached again to the guide hole 53, see FIG. 14m .The drill adjustment device 16 is then adjusted such that the length 31of the guide channel 54 is shortened. This may for instance be done byturning the drill adjustment device 16 at a number of preset intervals,e.g. one, two or three times 200 μm, or any other number times any otherpreset interval, see also above, and FIG. 14 n.

The drilling and cutting procedure is then repeated; see points 7-8 andFIG. 14o , and the implant dummy 36 and dummy reference 37 used to checkthe drill depth again, see FIG. 14p . In FIG. 14p the top surface 43 andthe top edge of the dummy reference 37 lie flush with each other, seearrow. The recess in the bone then is of suitable depth and is ready toreceive the implant 10.

10. The implant 10 may be guided to the exact matching recess at thesite of implantation through the guide channel 54 of the guide body 13,or alternatively be placed at the site of implantation without theguide. The later alternative is shown in FIG. 14q for illustrativepurposes.

11. The mandrel 35 is then used, also either with or without supportfrom the guide channel 54 of the guide body 13, to hammer the implant inposition and firmly attach it to the bone. The mandrel 35 is placed ontop of the implant 10 and then a hammer or similar tool is used tohammer or push the mandrel 35 (as shown symbolically by the arrow) suchthat the implant is forced in place, see FIG. 14 s.

12. Lastly, the hammer tool 35 and the guide base 12 are removed, theimplant 10 is implanted at the site of cartilage damage, see FIG. 14t ,and the incision wound can be stitched.

Further Embodiments

Embodiments comprises a modular surgical kit for repair of diseasedcartilage at an articulating surface of a joint, for use with a medicalimplant (10), a grafted plug (600) or an artificial plug having animplant body (27, 627) with a predetermined cross-sectional profile(81), the modular surgical kit comprising; a guide base (12) having apositioning body (11) with a guide hole (53) through said positioningbody (11), wherein:

-   the positioning body (11) has a cartilage contact surface (50) that    is designed to fit the contour of cartilage or subchondral bone in    the joint in a predetermined area surrounding the site of diseased    cartilage;-   the guide hole (53) has a muzzle (29) on the cartilage contact    surface (50) at a position corresponding to the site of the diseased    cartilage; and-   a guide body (13) with a guide channel (54), the guide channel (54)    having a cross-sectional profile that is designed to correspond to    the cross-sectional profile (81) of the implant body (27, 627) and    having a muzzle 32;-   wherein-   the positioning body (11) may comprise means for releasably    connecting (47) to the guide body (13) such that, when connected,    the guide channel (54) is positioned in relation to the positioning    body (11) such that its muzzle (32) emanates at a site corresponding    to the site of implantation into the bone.

Variants of these embodiments comprises one or more of the features:

-   wherein the cartilage contact surface (50) is custom designed to fit    the contour of the cartilage or subchondral bone of a specific    patient;-   wherein the cartilage contact surface (50) is designed to fit the    contour of the cartilage or subchondral bone of an average patient;-   wherein the guide body (13) comprises at least two guide channels    (54), each guide channel (54) having a cross-sectional profile that    is designed to correspond to the respective cross-sectional profile    (81) of at least two implant bodies (27, 627);-   wherein the guide channel (54) is provided by a guide insert (8)    that is designed to fit in the guide body (13);-   further comprising a drill adjustment device (16) being arranged to    enable adjustment of the drill depth e.g. in certain length    intervals;-   wherein the positioning body (11) is arranged with at least one    breakage means (57) for enabling easy removal of part of the    positioning body (11) by tearing, fracturing or similar breakage,    such means (57) for example being provided by grooves, slots or    perforations or other weakening of the structure;-   wherein the positioning body (11) is arranged with at least one    attachment means (9) for enabling easy attachment of adaptors, pins    and other devices used during surgery, e.g. by snap fit, this    embodiment may further comprise adaptors (17) fitting the attachment    means (9), for enabling flexible attachment of pins and other    devices;-   further comprising an insert tool with a cross-sectional profile    that is designed to correspond to the cross-sectional profile of the    guide channel (54) with a tolerance enabling the insert tool to    slide within the guide channel (54);-   wherein the insert tool is a cartilage cutting tool 3 with a    cross-sectional profile that is designed to correspond to the    cross-sectional profile of the guide channel (54) with a tolerance    enabling the cartilage cutting tool 3 to slide within the guide    channel (54), and comprising a cutting blade with sharp cutting    edges 3 c able to cut the cartilage in a shape that substantially    corresponds to the cross-section (81) of the implant body (27);-   wherein the insert tool is a drill and bone remover (2) with a drill    and bone remover body 20 having a cross-sectional profile that is    designed to correspond to the cross-sectional profile of the guide    channel (54) with a tolerance enabling the drill and bone remover    (2) to slide within the guide channel (54), the drill and bone    remover (2) further comprising a central drill (22), for drilling a    bore to receive the extending post (23) of the implant (10), and a    bone remover (26) for cutting a recess in the bone to receive the    implant body (27) of the implant (10);-   wherein the insert tool is a mandrel (35) with a mandrel surface (35    a) that is designed to fit the articulate surface (15) of the    implant (10) and having a cross-sectional profile that is designed    to correspond to the cross-sectional profile of the guide channel    (54) with a tolerance enabling the mandrel (35) to slide within the    guide channel (54);-   further comprising an implant dummy 36 with an implant element 41    that is designed to match the implant body 27 and having a lower    surface 41 a that is a replica of the bone contact surface 21, but    comprising no extending post 23;-   further comprising a dummy reference 37 that is arranged to fit to,    and possibly releasably attach to, the guide hole 53 of the guide    base 12 and is arranged to receive the implant dummy 36, by being    provided with a channel 58.

Further Embodiments of Drill Bit

Embodiment describe an implant specific drill bit 202, see FIGS. 15-18b, which is a combination of a drill and bone remover that is used todrill a recess, a hole or bone cavity in the bone at the site ofcartilage damage, for example in a joint in a patient. The recess madeis in the same size and shape as the implant, or slightly smaller thanthe implant, and is intended to be used for fastening and/or implantingan implant with a press fit. A suitable implant 210 to be implantedaccording to the disclosure, see FIGS. 16b, 18b , comprises an extendingpost 223 and an implant body 227 and is to inserted in the recess formedusing the implant specific drill bit 202 according to the disclosure, inthe bone tissue 232 and cartilage tissue 234 in the joint, see FIG. 17.

The implant specific drill bit 202 according to the disclosure comprisesa drill and bone remover body 20, a central drill part 222 and a boneremover part 26, as shown in FIG. 15. The central drill part 222 extendsfrom the centre of the drill and the bone remover body 220 has aproximal end and a distal end and a longitudinal y-axis extendingbetween the proximal end and the distal end, i.e. corresponding to theposition of a centrally placed extending post 223 on an implant 210having a circular implant body 227 when the drill bit is used fordrilling a recess.

The implant specific drill bit 202 may for example have the followingmeasures: a drill and bone remover body 220 may be 3-40 mm or 5-40 mm indiameter approximately corresponding to the diameter of the specificimplant body 27, or for example 1-5% smaller diameter than the specificimplant. The drill and bone remover body 220 may have a length 322 of2-500 mm or 4 mm-3 cm or 4 mm-5 cm or a length which the drill bitsufficient support when used together with a guide tool in a guidechannel. The bone remover part 226 may have similar diameter than thebone remover body 220 or slightly less.

The central drill part 222 may be cylindrical or conical in shape and be0.7-10 mm in diameter (if conical shape, the diameter refers to thebroadest part) and have a length 272 of 2-300 mm mm or may have adiameter 252 20% less than the diameter of the drill and bone removerbody 220 or the bone remover part, see for example FIG. 17.

The bone remover part 226 comprises a cutting edge 228 and the cuttingedge may further comprise protruding flanges 320 which protrudes fromcutting edge surface with a length 324 approximately 0.3-3 mm and awidth 326 of 0.3-1.5 mm or 0.3-2 mm, see for example FIG. 17. Theprotruding flanges 320 is made of a material suitable for cutting bone,for example stainless steel and may have the same material as thecutting edge 28

In one alternative embodiment, as illustrated in FIG. 19b the angle 328between the cutting edge 228 and the longitudinal y-axis (70) of theimplant specific drill bit 202 is 90° or less.

If the implant to be implanted has a curved articulating surface 229 theangle 328 between the cutting edge 228 and the longitudinal y-axis (70)of the implant specific drill bit 202 is preferably 80° or less in orderto keep the volume of the implant body lower.

The implant specific drill bit further comprises a shaft 221 which mayhave suitable measures and shapes to fit for using together with adrilling machine.

The drill bit according to the disclosure is implant specific. Thediameter of the central drill part 222 is the same as, or slightlysmaller than, the diameter of the extending post 223 of the implant 210that is selected to be implanted in the joint. The bone remover 226 ofthe bone remover body 220 has a cutting edge 228 that is placedperipherally around the central drill part 22. The diameter of the boneremover 226 is the same as, or slightly smaller than, the diameter ofthe implant body 227 of the implant 210 that is to be implanted, thuscreating a recess that matches the implant body, in which the implantbody can be received. See FIGS. 16a and 16b and FIGS. 18a and 18b forschematic illustrations of an implant and an implant specific drill bit202 according to the disclosure. The cutting edge or blade 228 of thebone remover 226 and the central drill part 222 is hard enough forcutting or carving bone.

The implant specific drill bit 202 according to the disclosure may bemade of materials such as stainless steel. The cutting edge or blade 228of the implant specific drill bit or implant specific drill bit 202according to the disclosure is designed in the same shape as an implantbody which is selected to be implanted in the bone cavity made using theimplant specific drill bit.

The cutting edge or blade 228 of the implant specific drill bit 202 maybe flat (see FIG. 18a ) if the implant to be inserted comprises a flatbone contacting surface 238 or cutting edge or blade 228 may protrudefrom the bone remover forming flanges 220, see FIG. 16a if the implantbody 227 of the implant to be inserted comprises a cutting edge or blade228 formed as a protruding anchoring ring portion 236 or rim 36, seeFIG. 16b . The implant specific drill bit 202 according to thedisclosure is designed after the shape of the implant to be inserted.

The drill and bone remover body 220 is constructed for forming a bonecavity for an implant directly in a joint and may alternatively bedesigned to fit the inside of a guide instrument for example inside aguide channel of a guide body of a guide instrument, with a slighttolerance to allow a sliding movement of the implant specific drill bit202 in such a guide channel. The implant specific drill bit 202 may alsobe equipped with a depth gauge 207 and may be used together with a guidetool. The depth gauge 207 of the implant specific drill bit determinesthe depth of the created drill hole as well as the depth of the recessfor the implant body 27.

The cross-sectional profile of the drill and bone remover body 20, thebone remover part 26, the cutting edge 228 and the central drill part222 matches or is slightly smaller, for example 0.1-5 volume % smallerthan the cross-sectional profile of an implant 210 and its extendingpost 23, its implant body 227 and also matches the shape of the implantbody which further may comprise an anchoring ring portion 36. The fitensures the correct, desired placement of the implant specific drill bit202 on the cartilage surface and thus ensures the precise direction andplacement of the drill hole for the extending post 23, as well as therecess for the implant body 27, in the bone.

The depth of the drilling may be adjusted manually if an implantspecific drill bit 202 is used that does not comprise a depth gauge 207and if the drill bit is used without guidance of a guide tool.

A Design Method Designing the Implant Specific Drill Bit 202

A design method according to embodiments comprises the following steps;

-   -   determining or selecting a size and shape of an orthopedic        implant (10) comprising a circular shaped implant body (27) and        a centrally placed circular shaped extending post (23)    -   protruding from the bone contacting surface (38) in a        longitudinal y-axis (60) direction of the implant (10); and    -   a. designing the size and shape of said implant specific drill        bit (2) comprising a bone remover part (26), a central drill        part (22) and a cutting edge (28) located one surface of the        bone remover part (26), and wherein the central drill part (22)        protrudes from the cutting edge (28) surface in a longitudinal        y-axis (70) direction of the implant specific drill bit (2)        depending on the selected size and shape for said implant (10)        in determined or selected step a, wherein;    -   the width (40) of the broadest part of the bone remover (26) in        a side view corresponds to, or is slightly smaller than, the        diameter (50) of the implant body (27) of the implant (10) that        is to be implanted    -   the rotational volume and the length (72) of the central drill        part (22) corresponds to, or is slightly smaller than, the        diameter (52) of the extending post (23) of the implant (10)        that is to be implanted    -   the curvature of the cutting edge (28) that is placed anywhere        peripherally around or surrounding the central drill part (22)        of the implant specific drill bit (2) corresponds to the        curvature of the bone contacting surface (38) of the implant.

The rotational volume (239) is a fictive volume, which is illustrated inFIG. 20a , and which is achieved by rotating the implant specific drillbit 202 around its longitudinal axis 70. In embodiments the constructionof the drill bit is not symmetrical in shape as the construction of thespecific implant. The rotational volume of the implant specific drillbit is symmetrical and is designed to correspond to the volume of thespecific implant. This rotational volume (239) also corresponds to thevolume that is removed when the implant specific drill bit 202 accordingto the disclosure is used for drilling a cavity 230 in the bone and orthe cartilage in the joint. The rotational volume is therefore a copy ofthe volume and size and shape of the implant (comprising an implant bodyand the extending post etc., even though the implant drill bit 2, whennot rotated, may have another shape than the implant. See also FIG. 17.

The implant may be selected from a kit of implants of different shapesand sizes or may be designed to fit a specific cartilage damage in aspecific patient. Individually constructed implants are made byinvestigation of the joint using for example MR and then using that datato create an implant body which will be sufficient to repair thecartilage damage in that specific patient.

FIG. 20a shows an exemplified embodiment of an implant specific drillbit comprising a cutting edge on only one side of the longitudinaly-axis of the drill bit and having the rotational volume correspondingto the specific implant.

A design method according to the disclosure for designing the implantspecific drill bit 202 according to the disclosure may comprise a stepwherein the cutting edge 228 of the drill bit 202 is designed tocorrespond to the shape and curvature of an implant with a bonecontacting surface 238 which is flat or a an implant 210 with a bonecontacting surface 238 which comprises an protruding anchoring ringportion 36.

An implant with a protruding anchoring ring portion 236 is very wellanchored in the bone cavity since both the extending post and theprotruding anchoring ring portion 236 of the implant is contributing infastening of the implant placed in a joint.

The shape and size of the implant are calculated or selected dependenton the size and shape of the cartilage damage, and dependent on thecurvature of the contour of the cartilage and/or of the subchondral bonein the area substantially coinciding with the cartilage damage.

The following steps may be comprised in generating design parameters foran implant specific drill bit according to the disclosure:

Generating a cross-section for the bone remover part 226 of the implantspecific drill bit 202 dependent on and substantially corresponding tosaid determined cross-section of the implant body 227 of an implant 10.

The cross-section for the implant body is generated or selected from akit of implants to correspond to the cross-section shape determined forthe cartilage damage.

Generating a length and a cross-section profile for a specific drill bit222 wherein the specific drill bit 222 is extending from a cutting bladeor edge 228 of the implant specific drill bit 202 and is dependent on orcorresponding to, the length and cross-section profile for an extendingpost 223 of an implant. The size and shape of the extending post isselected automatically according to a predetermined scheme or isselected manually by an operator.

Generating the shape of a cutting blade or edge 228 of an implantspecific drill bit 202 may be flat or comprise protruding flanges 320depending on, or corresponding to the size and shape and curvature ofthe bone contacting surface 238 of an implant 10.

FIGS. 16a and 16b and also FIGS. 18a and 18b show examples of the sizeand shape of an implant specific drill bit 202 according to thedisclosure which is designed dependent of or corresponding to thedesign; the shape, size and curvature of an implant 10.

The length of the implant specific drill bit 202 is depending on theneed for a long or short shaft for attaching the drill bit to a drill.

The length of the drill and bone remover body 220 is selected dependenton the intended use of the implant specific drill bit 2. The length ispreferably longer than the depth or height of the implant body of theimplant intended to be implanted. For example a use of the implantspecific drill bit 202 inside a guide tool guiding and supporting thedrill bit may lead to a design of a drill and bone remover body 220which corresponds to the length of a guide channel of such a guide tool,for maximum support of the drill bit during drilling.

Determination of the cartilage damage and alternative embodimentsgenerating design parameters of a medical implant 210 and therebygenerating design parameters for an implant specific drill bit accordingto the present disclosure:

An image or a plurality of images representing a three dimensional imageof a bone member of the joint in a patient's limb is obtained byselecting one of a per se known imaging technology for non-invasiveimaging of joints, such as magnetic resonance imaging (MRI),computerized tomography (CT) imaging or a combination of both, or othersuitable techniques such as delayed Gadolinium-enhanced MRI of cartilage(dGEMRIC) techniques. The image of the joint should comprise arepresentation of cartilage in the joint as well as the underlyingsubchondral bone in the area of the cartilage damage. Image data makingup a three dimensional image representation of the joint is stored in adigital format in a manner that enables to keep track of the dimensionsof the real joint that the image depicts.

The image data is analyzed in a data processing system to identify anddetermine physical parameters for the cartilage damage. The physicalparameters to determine comprise the presence, the location and the sizeand shape of the cartilage damage, as well as curvature of the surfacecontour of the cartilage or the subchondral bone in an area of thecartilage damage.

In one embodiment of the inventive concept the design system operates todetermine physical parameters on images of the patient's individualjoint and the current cartilage damage, and thereby produces anindividually designed implants which shape and size is used as model fordesigning shape and size of the implant specific drill bit 202 accordingto the disclosure.

Further in one exemplified embodiment, the contour curvature for anarticulate surface of a substantially plate shaped implant body 227dependent on said determined surface curvature of the cartilage and/orthe subchondral bone.

The contour curvature for the articulate surface of the implant body isgenerated to correspond to the curvature that covers the cartilagedamage.

In another embodiment the design system operates on a collection ofimages of joints constituting a statistical basis for determiningphysical parameters for producing an implant 210 which then is used as amodel for designing an implant specific drill bit according to thedisclosure.

Embodiments comprises a design method designing an implant specificdrill bit (202) comprising:

-   determining or selecting a size and shape of an orthopedic implant    (210) comprising a circular shaped implant body (227) and a    centrally placed circular shaped extending post (223) protruding    from the bone contacting surface (238) in a longitudinal y-axis    (260) direction of the implant (210); and-   selecting design parameters for the implant specific drill bit (202)    by:

selecting the width (240) of the broadest part of the bone remover (226)in a side view to correspond to, or to be slightly smaller than, thediameter (250) of the implant body (227) of the specific implant (210)that is to be implanted

selecting the rotational volume and the length (272) of the centraldrill part (222) to correspond to, or to be slightly smaller than, thediameter (252) of the extending post (223) of the specific implant (210)that is to be implanted

selecting the curvature of the cutting edge (228) that is placedanywhere peripherally around or surrounding the central drill part (222)of the implant specific drill bit (202) to correspond to the curvatureof the bone contacting surface (238) of the implant.

In further embodiments the determining the size and shape of saidimplant may either be performed by:

-   selecting implants from a kit of implants of different predetermined    sizes; or

by individually designing the size and shape of an implant;

and wherein the size and shape of the selected implant is correspondingin large or partly or substantially to the size and shape of a cartilagedamage in a specific patient.

Further embodiments may comprise:

-   wherein said cutting edge (228) in side view is designed to    correspond to the shape of at least one side of the bone contacting    surface (238) in a cross-sectional view of the specific implant    (210); and wherein the bone contacting surface (238) is    substantially flat or a bone contacting surface (238) which    comprises an protruding anchoring ring portion (236).-   wherein the volume of the part of the designed implant specific    drill bit (202) which corresponds to fit the implant (210) is 0.1-5%    smaller than the volume of the implant (210) to be implanted,    allowing for press fit of the implant (210) placed in the recess    made by the implant specific drill bit (202) according to the    disclosure.-   wherein the cutting edge comprises at least one flange (220).-   wherein the flange has a length (224) of 0.3-3 mm protruding from    the cutting edge (2) and/or a width 0.3-2.0 mm or 0.3-2.0 mm    corresponding to the length (235) in a cross-sectional view of the    anchoring ring portion (236) of an implant (210).-   wherein the angle 328 between the cutting edge (228) and the    longitudinal y-axis (270) of the implant specific drill bit 202 is    designed to be 90° or less or for example 80° or less or 70° or less    based on the selected specific implant and its corresponding angle.-   wherein the length 272 of the central drill part (22) of the implant    specific drill bit is designed to be 2-300 mm corresponding to or    slightly longer, or 1-5% longer than the length (82) of the    extending post (23) of an specific implant (10).

Further embodiments may comprise an implant specific drill bit (202)designed according to the design method in any of the above embodimentsfor producing bone cavities for receiving orthopedic implants, saiddrill bit (202) comprises:

-   a drill and bone remover body (220) having a proximal end and a    distal end and a longitudinal axis extending between the proximal    end and the distal end; and-   a bone remover part (226) located in one end of the bone remover    body (220); and-   a central drill part (222) protruding from said bone remover part    (226);

wherein said bone remover part (226) comprises a cutting edge (228)which is placed peripherally around the central drill part (222). Thebone remover part (226) may comprise a flat surface or a surface whichfurther comprises flanges (320).

One embodiment comprises a kit comprising an implant specific drill bit(202) designed according to any of the above method embodiments and animplant 210, wherein said an implant specific drill bit (202) isdesigned to correspond to the size and shape of said implant (210).

FIG. 21 shows an image of a recess drilled in a cartilage coated bonetissue with a conventional drill, the edges of the recess is uneven andthe cartilage is frayed. Further, with conventional technology the edgesof recess in the cartilage may be misaligned relative the edges of therecess of the bone tissue. The embodiments described herein improve thealignment of the recesses in the cartilage and the bone tissue, as shownin FIG. 22.

FIG. 23 shows an embodiment of the lower part of a drill bit 202 havingsharp precutting edges 410 and 416 and shark fin shape cutting edges 412and 414. The precutting edges protrudes, for example in the range of 0.1to 1 mm such as 0.5 mm, in relation to the shark fin shape cutting edgesin order to cut through the cartilage before cutting the recess in thebone tissue. Different embodiments comprise one or more cutting edges,for example three or four cutting edges. In embodiments each shapecutting edge is paired with an associated sharp precutting edge. FIG.24a and FIG. 24b shows images of an embodiment of such a drill bit. InFIG. 24a the sharp cutting edges 410 and 414 are indicated, whereas FIG.24 b shows the drill bit turned 45 degrees around its rotational axisand the shark fin shape cutting edges 412 and 416 being visible. Inembodiments, the shark fins of the drill are longer, for example 0.2 mmlonger, than the shark fins (edges) of the implants hat in order toprovide a gap under the implant. In embodiments, the thickness of theshark fin edges is wider, for example 0.2 mm wider, than the shark fins(edges) of the implants hat in order to allow fitting the implant in therecess.

FIGS. 25a and 25b shows how the shape of the lower part of the drill 202corresponds to the bone contacting part of the implant 210.

Embodiments of the kit comprises a drill guide having guides for one,two or more adjacently positioned bores. The kit and/or its parts enablethe creation of a recess with desired angle or tilting in relation tothe surface of the cartilage and/or bone. The kit and/or its partsenable removal of tissue to match the geometry of an implant.Embodiments of the drill enables the drilling of a two parallel bores tomake a recess for an implant with a hat and an extending post.Embodiments of the drill comprises a drill body with 220 with a diametersmaller, for example 0.2 mm smaller, than the diameter of the hat of anassociated implant in order to provide a press fit of the implant in therecess in the bone tissue. Embodiments of the drill comprises a drillpeg 222 having a smaller diameter, for example 0.4 mm smaller, andhaving a longer extension, for example 2 mm longer, than the peg or postof an associated implant in order to provide a press fit for the implantwith the bone tissue. Embodiments of the drill comprises a sharp tip inorder to avoid slipping on the cartilage surface. Embodiments of thedrill comprises one or more flutes enabling removal of tissue duringdrilling. In embodiments of the drill, all or some of the edges of thedrill stop and/or shaft shall be broken/chamfered/rounded. Inembodiments, the large drill diameter and/or the drill peg has a part ofits peripheral surface area offset inwards in order to minimize frictionduring drilling.

Simulation of the Surface without Damage

FIGS. 26a-d and 27a-d show the design of the surface of an implanthaving a surface which corresponds to a three dimensional (3D) image ofa simulated healthy cartilage surface. A 3D model of the body partcomprising the damaged or diseased cartilage is generated based on MRIand/or CT images, which may be segmented. The damage in the cartilage,and possibly also damage in the subchondral bone, is then marked in the3D model. FIGS. 26a-d show the design of the surface of an implant witha circular surface area and FIGS. 27a-d show the design of the surfaceof an implant with a surface area corresponding to two overlappingcircles.

It is desirable to simulate a healthy cartilage surface as closely aspossible. In some prior art methods of implant design, the 3D curvatureof the subchondral bone subjacent to the area of damaged cartilage hasbeen used for designing the surface of the implant. However, since thecartilage does not necessarily have uniform thickness, this does notcorrespond to a simulated healthy cartilage surface.

According to embodiments of the disclosure, the implant surface isinstead simulated based on the curvature of the cartilage immediatelysurrounding the area of damaged cartilage. A suitable area comprisingand extending around the damaged cartilage is selected, and thecurvature of the whole area is simulated in such a way that thecurvature of the area which is not damaged matches the actual curvature,and a simulated healthy surface of the area of damaged cartilage isgenerated. The simulation may comprise an interpolation, e.g. using theSolid Works Surface Wizard or another suitable tool.

FIGS. 26a and 27a show an image of a 3D mesh model of the cartilage andbone of a knee. The mesh model may be created based on any suitableimaging methods, such as e.g. MRI. In the image of the mesh model, theimplant position has been marked with a circle in FIG. 26a , and twooverlapping circles, a combined or “twin” circle, in FIG. 27a . Thecircle, or “twin” circle, corresponds to the circumferential shape ofthe implant hat H of the implant to be used. At least parts of thesurface within this circle or “twin” circle comprises damaged cartilage,and possibly also damaged subchondral bone beneath the cartilage. Thesize of the implant hat H is selected based on the extent of damage, sothat at least most of the damaged area is removed and replaced by theimplant. Sometimes all of the surface within the circle will be damaged,and some of the damaged area will not be removed, and sometimes thevolume to be removed will comprise also some healthy cartilage and/orsubchondral bone.

FIGS. 26b and 27b show the selection of a suitable area for simulatingthe curvature of the surface. The area is preferably large enough tohave sufficient curvature in all directions surrounding the area ofdamaged cartilage, without containing any sharp edges which coulddistort the simulation. The area may e.g. be selected based on thedistance from the damaged cartilage and the curvature, e.g. so that thewhole area within a predetermined distance from the damaged cartilage isselected provided that the curvature within this area is below a certainthreshold. Sections falling within a predetermined distance from thedamaged cartilage but exceeding the curvature threshold would then beexcluded from the area.

FIGS. 26c and 27c show a simulation of the curvature of the whole area,including a tangent interpolation over the area of damaged cartilage.The generated surface is defined by curvature lines along the length andthe width, points along which curvature lines coincide with the pointsof the 3D mesh model in the areas of healthy cartilage. Only healthycartilage surfaces are used as a basis for this tangent interpolation;all potentially damaged areas are excluded. In FIGS. 26c and 27c , thehealthy mesh areas shown with triangles within the surface generatinggrid are used as a basis for the tangent interpolation, and the blankareas are excluded. Preferably, all areas of damaged cartilage areexcluded from being the basis of the interpolation. After theinterpolation, the deviation between the interpolated area and theactual area within the areas of healthy cartilage may be analyzed inorder to ascertain that the interpolated area does not differ too muchfrom the actual area in the areas of healthy cartilage. If there is toomuch deviation, a new interpolation may be necessary.

When the healthy cartilage surface has been simulated, the area istrimmed to match the implant size, as shown in FIGS. 26d and 27d . A 3Dmesh model of the cartilage and bone of the knee comprising the implantis then generated, so that it can be determined that the knee with theimplant matches the surrounding surfaces. This evaluation may e.g. bedone layer by layer in the MRI software.

The depth and the axis tilt of the implant may be optimized in order tominimize the total penetration of the implant into the bone. FIGS. 28a-bshow an implant with an implant hat H and an implant post/peg P,positioned at different depths and axis tilts in a joint. Theoptimization may be done by positioning the implant and tilting theimplant axis A so that the implant hat H will at all points be thickenough to ensure mechanical stability, and preferably also thick enoughto ensure firm anchoring towards cartilage and bone. This may mean thatthe implant hat H at each point of its circumference must penetrate atleast a predetermined minimum depth into the bone. This ensures that thewhole of the implant hat H will have at least a minimum thickness, andwill thus not easily break.

The optimization of the tilt of the implant axis A may involveminimizing the maximum penetration depth into the bone along thecircumference of the implant hat H. This ensures that the hole to bedrilled in the bone will not become deeper than necessary. Theoptimization of the tilt of the implant axis A may alternatively involveminimizing the total volume of bone and/or cartilage to be removed forimplanting the implant. This optimization is especially advantageouswhen implanting a combined, “twin”, implant having more than one implantaxis A. The optimization of the tilt of the implant axis A mayalternatively involve minimizing the surface area of the implantpenetration into the bone. The surface area may e.g. be determined bymultiplying the average depth of the hole to be drilled in the bone bythe circumference.

When the position and axis tilt of the implant has been determined inthis way, an implant may be designed to have dimensions according to thedetermined position and axis tilt, and a surface corresponding to thesimulated healthy cartilage surface described above in relation to FIGS.26a-d and 27a -d.

FIG. 29 shows an example of a surgical kit designed according to amethod of an embodiment of the present invention. This particularexemplifying embodiment of a surgical kit is especially adapted forcartilage replacement at the femur of a knee joint. The invention mayhowever be applied for cartilage replacement in an articulate surface inany other joint in the body, e.g. elbow, ankle, finger, hip, toe andshoulder. The surgical kit may e.g. comprise a height adjustment device16, a hammer tool/mandrel 35, a drill-bit or reamer-bit 2, an implantdummy 36, a guide tool 12, and an implant 10. A surgical kit mayadditionally comprise e.g. a cartilage cutting tool or cartilage cutter,a cartilage cut drill, a punch, a reamer guide, and/or a drill guide.

FIGS. 30-32 show different embodiments of a mandrel 35 having a gripportion 80 and a contacting surface 35 a designed to be in contact withan articulate surface 15 of an implant 10 during insertion of theimplant 10 by hammering, pressing and/or pushing the implant 10 intoposition in a recess made in a joint. The contacting surface 35 a of themandrel 35 is preferably designed to have an inverted surface to thearticulate surface 15 of the implant 10 to be implanted. The mandrel 35preferably comprises an element and/or a positioning mark 75 forrotational positioning of the mandrel 35 in the recess. The elementand/or positioning mark 75 is preferably arranged to allow thesimultaneous rotational positioning of the implant 10 in the recess. Thecontacting surface 35 a of the mandrel 35 is preferably the same size,or slightly smaller than, the surface 15 of the implant 10 to beimplanted. If the contacting surface 35 a of the mandrel 35 has across-sectional profile that has a tolerance with respect to thecross-sectional profile of the implant 10 to be inserted into the recessusing the mandrel 35, this may prevent the mandrel 35 from coming intocontact with the surrounding cartilage during insertion of the implant10 into the recess. The contacting surface ₃₅a of the mandrel ₃₅ is thuspreferably slightly smaller than the articulate surface 15 of theimplant 10 all around the circumference. The diameter of the surface 35a may be larger or smaller than the diameter of the grip portion 80 ofthe mandrel 35.

The mandrel shown in FIG. 32 is intended for use with an implant 10formed from two substantially circular shapes such that each of saidsubstantially circular shapes is partly overlapping the othersubstantially circular shape.

The mandrel 35 shown in FIGS. 30-32 further comprises a grip portion 80,which is intended to provide a good grip for the surgeon using themandrel 35. The grip portion 80 is preferably shaped to be thicker inthe middle, and have a smaller diameter close to the contacting surface38 than at the middle of the grip portion 80. It is an advantage todesign the mandrel so that the point of gravity lies in the hand of thesurgeon using the mandrel 35 rather than close to the contacting surface38. Further, if the grip portion 80 has a larger diameter towards themiddle, it may lie better in the hand of the surgeon.

FIG. 33a shows an example of a medical implant 10 of a surgical kitaccording to one or more embodiments of the invention provided with apositioning mark 90. The plate shaped implant body has an articulatesurface (first surface) 15 configured to face the articulating part ofthe joint and a bone contact surface (second surface) configured to facebone structure in the joint. The plate shaped implant body has across-section that substantially corresponds to the area of the damagedcartilage and the articulate surface 15 has a curvature thatsubstantially corresponds to the curvature of a healthy articulatesurface at the site of diseased cartilage. The extending post extendsfrom the bone contact surface. Since the implant 10 of the inventiveconcept is custom made for a specific patient, FIG. 33a is anexemplifying schematic picture displaying an embodiment of the implant10. Between the articulate surface 15 and the bone contact surface thereis a cartilage contacting surface.

The implant is specially designed, depending on the knees appearance andthe shape of the damage and in order to resemble the body's own parts,having a surface which preferably corresponds to a three dimensional(3D) image of a simulated healthy cartilage surface. The implant will betailor-made to fit each patient's damaged part of the joint.

The implant body is substantially plate shaped, meaning that theshortest distance crossing the surface 15 of the implant body issubstantially larger, e.g. at least 1.5 times larger than the thicknessof the implant body. By substantially plate shaped is meant that theimplant body may be substantially flat or may have some curvature,preferably a 3D curvature of the articulate surface 15. The articulatesurface 15 may for example have a curvature that corresponds to asimulated healthy cartilage reconstructed from an image taken e.g. withMRI or CT-scanning of the damaged cartilage surface of the joint. Oncethe implant 10 is placed in the joint there will be a surface with noparts of the implant pointing up from or down below the surroundingcartilage—the implant is incorporated to give a smooth surface.

The area and the shape of the implant surface 15 are individualdepending on the size of cartilage damage and location of the cartilagedamage. The area and shape of the implant can be decided by the surgeonhimself or be chosen from predetermined shapes. For instance thecross-section of the implant body may have a circular or roughlycircular, oval, triangular, square or irregular shape, preferably ashape without sharp edges.

In general, small implants are preferred since they have a smallerimpact on the joint at the site of incision and are also more easilyimplanted using arthroscopy or smaller open surgical procedures. Theprimary factor for determining the size of the implant is however thenature of the lesion to be repaired.

The implant replaces an area of damaged cartilage in an articulatesurface of a joint. Before the implant is placed in the desiredposition, the damaged cartilage is removed and also a part of the bonebeneath, i.e. a recess fitting the implant is made in the bone. Therecess can e.g. be drilled in the bone to fit the implant structure. Theextending post or rod-part of the implant 10 is used for securing theimplant 10 in the drilled hole of the bone. The length of the extendingpost, extending from the implant head, is adjusted to a length needed tosecure the implant 10 in the bone. The extending post is intended togive a primary fixation of the implant 10. It provides mechanicalattachment of the implant 10 to the bone in immediate connection withthe surgical operation.

FIG. 33b shows another example of a medical implant 10 of a surgical kitaccording to one or more embodiments of the invention, where the implant10 comprises two substantially circular shapes 92, where one of thecircular shapes 92 is provided with a positioning mark 90 on itsarticulate surface 15.

The positioning mark 90 on the articulate surface 15, i.e. the topsurface 15 facing the articulating part of the joint, of the medicalimplant 10 illustrated in FIGS. 33a-b is designed to be used fordetermining the orientation in which the implant 10 is to be placed in arecess made in a damaged articulate surface of a joint.

The positioning mark 90 may be designed so that the direction of thepositioning mark 90 is determining the placement orientation of theimplant 10 in a recess, in that the placement orientation of thepositioning mark 90 is also to be indicated by a mark made on the sideof a recess made in the articulate surface of a joint in which theimplant 10 is to be inserted, thereby providing for a correct or moreaccurate orientation of the implant when inserted in the recess made ina damaged articulate surface of a joint.

The positioning mark 90 on the articulate surface 15, i.e. the topsurface 15 facing the articulating part of the joint, of the implant 10may be designed so that the direction of the positioning mark 90 isdesigned to be pointing in an anatomic dependent direction in relationto a recess made in the articulate surface of a joint in which theimplant 10 is to be inserted, thereby providing for a correct or moreaccurate orientation of the implant 10 when inserted in the recess madein a damaged articulate surface of a joint.

FIG. 34 shows a guide tool 12 according to one or more embodiments ofthe invention. The guide tool 12 preferably has a cartilage contactsurface that has a shape and contour that is designed to correspond toand to fit the contour of the cartilage or the subchondral bone in thejoint in a predetermined area surrounding the site of diseasedcartilage. The guide tool 12 aids with exact precision removal of avolume of cartilage and subchondral bone, and preferably has a guidechannel 54. The guide tool 12 preferably comprises a positioning mark96, comprised in the structure of the guide tool 12, wherein thepositioning mark 96 is aligned with the centre of the guide channel 54in a joint axis direction. The guide tool 12 may also comprise anindentation 97 that enables marking of the cartilage surface in theposition of the positioning mark 96.

FIG. 35 shows a guide tool 12 according to one or more embodiments ofthe invention comprising an implant dummy 36 placed inside the guidechannel 54 of the guide tool 12. The guide tool 12 may be placed in thejoint using pins 95 for stabilization and fastening.

The guide channel 54 is used for stabilizing tools that are to beinserted into the guide channel 54, such as e.g. a drill bit 2 and/or animplant dummy 36. The guide channel 54 therefore preferably has an innercross-sectional profile that is designed to correspond to thecross-section of the drill bit 2 and/or the implant dummy 36. In otherwords, the drill bit 2 and/or the implant dummy 36 fits the guidechannel 54, with a slight tolerance to allow a sliding movement of thedrill bit 2 and/or the implant dummy 36 in the guide channel 54.

The guide channel 54 has an opening on the cartilage contact surface,arranged to be placed in a position corresponding to the site of thediseased cartilage in a joint. The height of the guide channel 54 mustbe sufficiently long to give support to the tools used inside the guidechannel 54. The height of the guide channel 54 may e.g. be between 1 and10 cm, preferably 3-10 cm, and always sufficiently high to ensurestabilization of the tools that are to be inserted into the guidechannel 54. In one embodiment, the top of the guide channel 54 isdesigned to project above the tissue surrounding the surgery cut whenthe guide tool is placed on the cartilage in a joint during surgery.

The guide tool 12 is easy to place due to the precise fit of thecartilage contact surface on the cartilage surface. The size and shapeof cartilage contact surface of the guide tool 12 is determineddepending on the size and shape of the damaged cartilage and thus on thecross section of the implant body 10, and also depending on the positionof the cartilage area in a joint. The size, shape or spread of thecartilage contact surface of the guide tool 12 is a considerationbetween the following aspects; minimize surgery lesion, maximizestability for guide tool 12, anatomic limitations on the site of theinjury. Not all cartilage surfaces in a joint can be used for placementof the guide tool 12. A large spread of the cartilage contact surface ispreferable to get good stability of the guide tool 12, however, a largesurface area of the surface may also lead to a large surgicalintervention which is undesired.

Thus, the size of the guide tool 12 is determined by a balance betweenthe desire to achieve good positioning stability and small surgicaloperations. Also, the cartilage contact surface need not have acontinuous, regular shape, but may have an irregular shape, as long asit gives adequate support and stable positioning of the guide tool 12.The cartilage contact surface may also consist of three separatedpoints.

FIG. 36 shows the use of a mandrel 35 for for hammering, pressing and/orpushing an implant 10 into position in a recess made in a joint,according to one or more embodiments of the invention. FIG. 36 alsoshows a positioning mark indicated on the cartilage surface. Thepositioning mark is preferably added to the cartilage surface when theguide tool 12 is placed in the joint, e.g. by inserting a marking peninto the indentation 97 in the guide tool 12.

The implant 10 is placed in the recess, rotated so that the positioningmark 90 of the implant 10 corresponds to the positioning mark indicatedon the cartilage surface. The element and/or positioning mark 75 on themandrel 35 is then preferably aligned with the positioning mark 90 onthe implant 10 and the positioning mark indicated on the cartilagesurface.

The element and/or a positioning mark 75 on the mandrel 35 is preferablydesigned to allow the surgeon to view the the positioning mark 90 of theimplant 10 when the mandrel 35 is used for hammering, pressing and/orpushing the implant 10 into position in a recess.

In embodiments, the method for inserting an implant 10 into a recess byuse of a mandrel 35 further comprises: providing a guide tool 12comprising a positioning feature/mark 96; and making, by one of asurgeon and a mechanical arm such as a robot arm, a mark on the side ofa recess made in an articulate surface of the joint in the direction ofthe positioning mark of said guide tool 12, thereby determining thefuture placement orientation of the implant 10.

The surgical kit may also comprise a height adjustment device 16, e.g.comprising a male part 47 and a female receiving part 48 which when usedtogether allows for stepwise adjustment of drill depth.

The male part 47 is in the outermost position in a zero-mode and mayfrom there be adjusted inwards allowing the surgeon to for example makestepwise deeper drill holes. When the height adjustment device 16 is instarting mode or outermost zero-mode, the position marking of the guidetool 12 and the positioning marking of the height adjustment device 16are aligned.

Thus, by being able to adjust the length of the guide channel 54, thesurgeon is also able to adjust the depth of drilling and cutting intothe bone. The length of the guide channel 54 may be varied since theguide tool 12 and the height adjustment device 16 are able to move inrelation to one another. Further, the male part 47 and the femalereceiving part 48 of the height adjustment device 16 may be arrangedsuch that the length of the guide channel 54 may be varied at certainstepwise intervals, e.g. at 200 μm or at 100-300 μm intervals or steps,or any other desired interval. For example, the height might be adjustedbetween for example 0.2-3 mm, in one or several steps. This may forinstance be achieved by arranging the male part 47 inside the femalereceiving part 48 of the height adjustment device 16 such that the malepart 47 insert tool to have a cross-sectional profile that correspondsto the cross-sectional profile of the guide channel of the female part48 with a tolerance enabling the insert tool to slide within the guidechannel of the female part 48.

The insert tool may e.g. be placed in a starting position where both thepositioning mark of the insert tool is aligned with the positioning mark96 of the guide tool 12.

1. A design method for designing a mandrel for hammering, pressingand/or pushing an implant into position in a recess made in a joint andfirmly attach the implant to the bone of a patient, the mandrelcomprising a contacting surface adapted to be in contact with anarticulate surface of the implant to be inserted, the method comprisingdesigning the contacting surface of the mandrel to fit the articulatesurface of the implant in that the contacting surface of the mandrel hasa cross-sectional profile corresponding to the cross-sectional profileof the implant.
 2. The design method according to claim 1, comprisingdesigning at least a portion of the mandrel surface to have an invertedsurface, or essentially inverted surface, to the curvature of thearticulate surface of the implant to be inserted.
 3. The design methodaccording to claim 1, comprising designing the cross-sectional profileof the contacting surface of the mandrel to have a tolerance in relationto the cross-sectional profile of the articulate surface of the implantin order to prevent the mandrel from coming into contact with thesurrounding cartilage during insertion of the implant into the recess.4. The design method according to claim 1, comprising: receiving imagedata representing a three-dimensional image of a joint; identifyingcartilage damage in the image data; determining the position of animplant to be used for cartilage repair; simulating a healthy surface ofthe area of damaged cartilage at the determined implant position;designing the articulate surface of the implant to match the simulatedhealthy surface; and determining the mandrel surface to have at leastone of a corresponding and an inverted curvature to the curvature of thearticulate surface of the implant.
 5. The design method of claim 1,comprising: determining the position of at least one element and/orpositioning mark of the mandrel; and designing said at least one elementand/or positioning mark of the mandrel to be adapted for rotationalpositioning of the mandrel in relation to the implant.
 6. The designmethod of claim 1, comprising designing at least one element and/orpositioning mark of the mandrel to be adapted for rotational positioningthe mandrel so that the mandrel surface fits the articulate surface ofthe implant.
 7. The design method of claim 1, comprising designing atleast one element and/or positioning mark of the mandrel to be adaptedfor rotational positioning the mandrel in relation to a positioning markof the implant.
 8. The design method of claim 1, comprising designing atleast one element and/or positioning mark of the mandrel to be adaptedfor rotational positioning the mandrel in relation to a positioning markto be made on the side of the recess where the implant is to beinserted.
 9. The design method of claim 1, comprising designing at leastone element and/or positioning mark of the mandrel to be pointing in ananatomic dependent direction, said at least one element and/orpositioning mark thereby indicating a correct orientation of the mandrelwhen inserted into the recess where the implant is to be inserted. 10.The design method of claim 1, wherein the implant is an individuallycustomized implant designed with an articulate surface having a shapeand curvature which is simulating a healthy surface at the determinedimplant position where the implant is to be inserted, comprisingdesigning at least one element and/or positioning mark of the mandrel tobe adapted for rotational positioning the mandrel in relation to atleast one element and/or positioning mark of the implant and apositioning mark to be made on the side of a recess.
 11. The designmethod of claim 1, wherein the articulate surface of the implant isdesigned to match a healthy surface at the determined implant positionand the healthy surface is simulated based on image data representing athree-dimensional image of a joint and the curvature of the cartilageimmediately surrounding the area of damaged cartilage.
 12. The designmethod of claim 1, wherein the contacting surface of the mandrel isdesigned to be a corresponding surface to a healthy surface at adetermined implant position of a joint and the healthy surface issimulated based on image data representing a three-dimensional image ofthe joint and the curvature of the cartilage immediately surrounding thearea of damaged cartilage.
 13. The design method of claim 1, wherein thecontacting surface of the mandrel is designed to be an inverted surfaceto a healthy surface at a determined implant position of a joint, andthe healthy surface is simulated based on image data representing athree-dimensional image of the joint and the curvature of the cartilageimmediately surrounding the area of damaged cartilage.
 14. The designmethod of claim 1, further comprising providing at least one elementand/or a positioning mark on the mandrel such that the positioning markis visible for a surgeon and is adapted to be used for indicating arotational position of the mandrel in relation to the implant to thesurgeon.
 15. The design method of claim 1, further comprising providingat least one element and/or a positioning mark on the mandrel as amarking, such as e.g. a dot, or groove in the circumference of thecontacting surface of the mandrel.
 16. A mandrel for hammering, pressingand/or pushing an implant in position and firmly attach an implant tothe bone of a patient, said mandrel comprising a contacting surface thatfits the articulate surface of an implant to be inserted using themandrel in that the mandrel has a corresponding cross-sectional profileto the articulate surface of the implant.
 17. The mandrel of claim 16,wherein the contacting surface of the mandrel is an inverted surface tothe curvature of the articulate surface of the implant to be inserted ina joint using the mandrel.
 18. The mandrel of claim 16, furthercomprising at least one element and/or positioning mark adapted forrotational positioning of the mandrel in relation to at least one of ananatomic dependent direction, at least one element and/or positioningmark on the surface of the implant, an element and/or a positioning markof the guide tool, and a mark to be made on side of a recess to be madeat the determined implant position.
 19. The mandrel of claim 16, whereinsaid at least one element and/or positioning mark for rotationalpositioning the mandrel includes at least one of a protrusion, a groove,a notch, a recess, a hole, a marking or shape fit element adapted forrotational positioning the mandrel.
 20. The mandrel of claim 16, furthercomprising a grip portion that has a smaller diameter close to thecontacting surface than at the middle of the grip portion, in order forthe point of gravity to lie in the hand of the surgeon using themandrel.